; Do not overwrite preexisting contents of unread-command-events

28 files changed, 100 insertions, 66 deletions

diff --git a/lisp/comint.el b/lisp/comint.el
index de220619751..7db297a1427 100644
--- a/lisp/comint.el
+++ b/lisp/comint.el
@@ -1051,7 +1051,7 @@ See also `comint-read-input-ring'."
       (let ((ch (read-event)))
         (if (eq ch ?\s)
             (set-window-configuration conf)
-          (setq unread-command-events (list ch)))))))
+          (push ch unread-command-events))))))
 
 
 (defun comint-regexp-arg (prompt)
@@ -3365,7 +3365,8 @@ the completions."
             (set-window-configuration comint-dynamic-list-completions-config))
         (if (eq first ?\s)
             (set-window-configuration comint-dynamic-list-completions-config)
-          (setq unread-command-events (listify-key-sequence key)))))))
+          (setq unread-command-events
+                (nconc (listify-key-sequence key) unread-command-events)))))))
 
 (defun comint-get-next-from-history ()
   "After fetching a line from input history, this fetches the following line.
diff --git a/lisp/double.el b/lisp/double.el
index b06f59cf6a6..ee511e55963 100644
--- a/lisp/double.el
+++ b/lisp/double.el
@@ -122,9 +122,10 @@ but not `C-u X' or `ESC X' since the X is not the prefix key."
                          (append (make-list (1- (length (nth 1 entry)))
                                             127)
                                  (nth 2 entry)
-                                 '(magic-end)))
+                                 '(magic-end)
+                                 unread-command-events))
                    (vector 127))
-               (setq unread-command-events (list new))
+               (push new unread-command-events)
                [ignore])))
           ((eq key 'magic-end)
            ;; End of double event.  Ignore.
@@ -134,7 +135,8 @@ but not `C-u X' or `ESC X' since the X is not the prefix key."
            (let ((exp (nth 1 (assoc key double-map))))
              (setq double-last-event key)
              (setq unread-command-events
-                   (append (substring exp 1) '(magic-start)))
+                   (append (substring exp 1) '(magic-start)
+                           unread-command-events))
              (vector (aref exp 0)))))))
 
 ;;; Mode
diff --git a/lisp/ebuff-menu.el b/lisp/ebuff-menu.el
index 337ea10f26d..93418063d10 100644
--- a/lisp/ebuff-menu.el
+++ b/lisp/ebuff-menu.el
@@ -133,7 +133,7 @@ Run hooks in `electric-buffer-menu-mode-hook' on entry.
             (setq select
                   (catch 'electric-buffer-menu-select
                     (message "<<< Type SPC or RET to bury the buffer list >>>")
-                    (setq unread-command-events (list (read-event)))
+                    (push (read-event) unread-command-events)
                     (let ((start-point (point))
                           (first (progn (goto-char (point-min))
                                         (unless Buffer-menu-use-header-line
@@ -210,7 +210,9 @@ See the documentation of `electric-buffer-list' for details."
 
 (defun Electric-buffer-menu-exit ()
   (interactive)
-  (setq unread-command-events (listify-key-sequence (this-command-keys)))
+  (setq unread-command-events
+        (nconc (listify-key-sequence (this-command-keys))
+               unread-command-events))
   ;; for robustness
   (condition-case ()
       (throw 'electric-buffer-menu-select nil)
diff --git a/lisp/ehelp.el b/lisp/ehelp.el
index 66e4f5c633b..2e15af34a81 100644
--- a/lisp/ehelp.el
+++ b/lisp/ehelp.el
@@ -204,10 +204,10 @@ BUFFER is put back into its original major mode."
   (catch 'exit
     (if (pos-visible-in-window-p (point-max))
         (progn (message "%s" (substitute-command-keys "<<< Press Space to bury the help buffer, Press \\[electric-help-retain] to retain it >>>"))
-               (if (equal (setq unread-command-events (list (read-event)))
-                          '(?\s))
-                   (progn (setq unread-command-events nil)
-                          (throw 'exit t)))))
+               (let ((ev (read-event)))
+                 (if (equal ev ?\s)
+                     (throw 'exit t)
+                   (push ev unread-command-events)))))
     (let (up down both neither
           (standard (and (eq (key-binding " " nil t)
                              'scroll-up)
diff --git a/lisp/eshell/em-hist.el b/lisp/eshell/em-hist.el
index 1cdf6d69714..9f070c33db3 100644
--- a/lisp/eshell/em-hist.el
+++ b/lisp/eshell/em-hist.el
@@ -520,7 +520,7 @@ See also `eshell-read-history'."
         (let ((ch (read-event)))
           (if (eq ch ?\ )
               (set-window-configuration conf)
-            (setq unread-command-events (list ch))))))))
+            (push ch unread-command-events)))))))
 
 (defun eshell-hist-word-reference (ref)
   "Return the word designator index referred to by REF."
diff --git a/lisp/gnus/gnus-art.el b/lisp/gnus/gnus-art.el
index d83eaddf165..ffe9a211417 100644
--- a/lisp/gnus/gnus-art.el
+++ b/lisp/gnus/gnus-art.el
@@ -6871,11 +6871,13 @@ KEY is a string or a vector."
       (with-current-buffer gnus-article-current-summary
         (setq unread-command-events
               (if (featurep 'xemacs)
-                  (append key nil)
-                (mapcar (lambda (x) (if (and (integerp x) (>= x 128))
-                                        (list 'meta (- x 128))
-                                      x))
-                        key)))
+                  (append key unread-command-events)
+                (nconc
+                 (mapcar (lambda (x) (if (and (integerp x) (>= x 128))
+                                         (list 'meta (- x 128))
+                                       x))
+                         key)
+                 unread-command-events)))
         (let ((cursor-in-echo-area t)
               gnus-pick-mode)
           (describe-key (read-key-sequence nil t))))
@@ -6893,11 +6895,13 @@ KEY is a string or a vector."
       (with-current-buffer gnus-article-current-summary
         (setq unread-command-events
               (if (featurep 'xemacs)
-                  (append key nil)
-                (mapcar (lambda (x) (if (and (integerp x) (>= x 128))
-                                        (list 'meta (- x 128))
-                                      x))
-                        key)))
+                  (append key unread-command-events)
+                (nconc
+                 (mapcar (lambda (x) (if (and (integerp x) (>= x 128))
+                                         (list 'meta (- x 128))
+                                       x))
+                         key)
+                 unread-command-events)))
         (let ((cursor-in-echo-area t)
               gnus-pick-mode)
           (describe-key-briefly (read-key-sequence nil t) insert)))
diff --git a/lisp/info.el b/lisp/info.el
index 48d9d1981af..0a2206d61bf 100644
--- a/lisp/info.el
+++ b/lisp/info.el
@@ -3825,7 +3825,7 @@ with a list of packages that contain all specified keywords."
                     (message (if flag "Type Space to see more"
                                "Type Space to return to Info"))
                     (if (not (eq ?\s (setq ch (read-event))))
-                        (progn (setq unread-command-events (list ch)) nil)
+                        (progn (push ch unread-command-events) nil)
                       flag))
         (scroll-up)))
     (bury-buffer "*Help*")))
diff --git a/lisp/international/quail.el b/lisp/international/quail.el
index 90a540aae30..f60af4ab9b6 100644
--- a/lisp/international/quail.el
+++ b/lisp/international/quail.el
@@ -1415,7 +1415,8 @@ Return the input string."
               ;; KEYSEQ is not defined in the translation keymap.
               ;; Let's return the event(s) to the caller.
               (setq unread-command-events
-                    (string-to-list (this-single-command-raw-keys)))
+                    (append (this-single-command-raw-keys)
+                            unread-command-events))
               (setq quail-translating nil))))
         (quail-delete-region)
         quail-current-str)
@@ -1491,7 +1492,8 @@ Return the input string."
               ;; KEYSEQ is not defined in the conversion keymap.
               ;; Let's return the event(s) to the caller.
               (setq unread-command-events
-                    (string-to-list (this-single-command-raw-keys)))
+                    (append (this-single-command-raw-keys)
+                            unread-command-events))
               (setq quail-converting nil))))
         (setq quail-translating nil)
         (if (overlay-start quail-conv-overlay)
diff --git a/lisp/international/robin.el b/lisp/international/robin.el
index 8254180fcc1..0ef90b18932 100644
--- a/lisp/international/robin.el
+++ b/lisp/international/robin.el
@@ -466,7 +466,7 @@ While this input method is active, the variable
           (list key)
         (delete-region start (point))
         (if key
-            (setq unread-command-events (list key)))
+            (push key unread-command-events))
         (if (stringp output)
             (string-to-list output)
           (list output))))))
diff --git a/lisp/kmacro.el b/lisp/kmacro.el
index 327cf455e65..9636a36b1e2 100644
--- a/lisp/kmacro.el
+++ b/lisp/kmacro.el
@@ -432,7 +432,7 @@ Optional arg EMPTY is message to print if no macros are defined."
       (setq last-input-event nil)))
   (when last-input-event
     (clear-this-command-keys t)
-    (setq unread-command-events (list last-input-event))))
+    (push last-input-event unread-command-events)))
 
 
 (defun kmacro-get-repeat-prefix ()
diff --git a/lisp/language/hanja-util.el b/lisp/language/hanja-util.el
index 8b62ee707f3..c9501d2ef8f 100644
--- a/lisp/language/hanja-util.el
+++ b/lisp/language/hanja-util.el
@@ -6585,7 +6585,9 @@ The value is a hanja character that is selected interactively."
                      (cmd (lookup-key hanja-keymap seq)))
                 (if (functionp cmd)
                     (funcall cmd)
-                  (setq unread-command-events (listify-key-sequence seq))
+                  (setq unread-command-events
+                        (nconc (listify-key-sequence seq)
+                               unread-command-events))
                   (throw 'exit-input-loop nil))))))
       (setq hanja-conversions nil))))
 
diff --git a/lisp/leim/quail/hangul.el b/lisp/leim/quail/hangul.el
index 12d7358841b..56a244f4574 100644
--- a/lisp/leim/quail/hangul.el
+++ b/lisp/leim/quail/hangul.el
@@ -410,7 +410,9 @@ When a Korean input method is off, convert the following hangul character."
                       ((commandp cmd)
                        (call-interactively cmd))
                       (t
-                       (setq unread-command-events (listify-key-sequence seq))
+                       (setq unread-command-events
+                             (nconc (listify-key-sequence seq)
+                                    unread-command-events))
                        (throw 'exit-input-loop nil))))))
         (quail-delete-overlays)))))
 
@@ -454,7 +456,9 @@ When a Korean input method is off, convert the following hangul character."
                       ((commandp cmd)
                        (call-interactively cmd))
                       (t
-                       (setq unread-command-events (listify-key-sequence seq))
+                       (setq unread-command-events
+                             (nconc (listify-key-sequence seq)
+                                    unread-command-events))
                        (throw 'exit-input-loop nil))))))
         (quail-delete-overlays)))))
 
@@ -499,7 +503,9 @@ When a Korean input method is off, convert the following hangul character."
                       ((commandp cmd)
                        (call-interactively cmd))
                       (t
-                       (setq unread-command-events (listify-key-sequence seq))
+                       (setq unread-command-events
+                             (nconc (listify-key-sequence seq)
+                                    unread-command-events))
                        (throw 'exit-input-loop nil))))))
         (quail-delete-overlays)))))
 
diff --git a/lisp/leim/quail/japanese.el b/lisp/leim/quail/japanese.el
index fd6628b8a45..831725f8065 100644
--- a/lisp/leim/quail/japanese.el
+++ b/lisp/leim/quail/japanese.el
@@ -59,8 +59,9 @@
                  (setq quail-current-str (aref quail-current-key 0))))
           (if (integerp control-flag)
               (setq unread-command-events
-                    (string-to-list
-                     (substring quail-current-key control-flag)))))))
+                    (append
+                     (substring quail-current-key control-flag)
+                     unread-command-events))))))
   control-flag)
 
 ;; Convert Hiragana <-> Katakana in the current translation region.
@@ -103,7 +104,7 @@
 
 (defun quail-japanese-self-insert-and-switch-to-alpha (key idx)
   (quail-delete-region)
-  (setq unread-command-events (list (aref key (1- idx))))
+  (push (aref key (1- idx)) unread-command-events)
   (quail-japanese-switch-package "q" 1))
 
 (defvar quail-japanese-switch-table
diff --git a/lisp/leim/quail/lao.el b/lisp/leim/quail/lao.el
index 52357afd8dd..14cf9268287 100644
--- a/lisp/leim/quail/lao.el
+++ b/lisp/leim/quail/lao.el
@@ -36,8 +36,9 @@
             (buffer-substring (overlay-start quail-overlay)
                               (overlay-end quail-overlay))
             unread-command-events
-            (string-to-list
-             (substring quail-current-key control-flag)))
+            (append
+             (substring quail-current-key control-flag)
+             unread-command-events))
     (setq quail-current-str
           (compose-string (quail-lookup-map-and-concat quail-current-key))))
   control-flag)
diff --git a/lisp/leim/quail/lrt.el b/lisp/leim/quail/lrt.el
index 342b52d6ab6..ed9138d2134 100644
--- a/lisp/leim/quail/lrt.el
+++ b/lisp/leim/quail/lrt.el
@@ -41,8 +41,9 @@
             (buffer-substring (overlay-start quail-overlay)
                               (overlay-end quail-overlay))
             unread-command-events
-            (string-to-list
-             (substring quail-current-key control-flag)))
+            (append
+             (substring quail-current-key control-flag)
+             unread-command-events))
     (let ((lao-str (lao-transcribe-roman-to-lao-string quail-current-key)))
       (if (> (aref lao-str 0) 255)
           (setq quail-current-str lao-str)
diff --git a/lisp/leim/quail/tibetan.el b/lisp/leim/quail/tibetan.el
index 1313f566def..5dacf290c10 100644
--- a/lisp/leim/quail/tibetan.el
+++ b/lisp/leim/quail/tibetan.el
@@ -50,8 +50,9 @@
             (buffer-substring (overlay-start quail-overlay)
                               (overlay-end quail-overlay))
             unread-command-events
-            (string-to-list
-             (substring quail-current-key control-flag)))
+            (append
+             (substring quail-current-key control-flag)
+             unread-command-events))
     ;; Special treatment of "-d..." and "-y...".
     (if (string-match "^-[dy]" quail-current-key)
         (setq quail-current-key (substring quail-current-key 1)))
@@ -381,8 +382,9 @@
             (buffer-substring (overlay-start quail-overlay)
                               (overlay-end quail-overlay))
             unread-command-events
-            (string-to-list
-             (substring quail-current-key control-flag)))
+            (append
+             (substring quail-current-key control-flag)
+             unread-command-events))
     (let ((transcription (quail-tibkey-to-transcription quail-current-key)))
       (if (> (length transcription) 0)
           (let ((quail-current-key transcription))
diff --git a/lisp/obsolete/terminal.el b/lisp/obsolete/terminal.el
index 6bab61b0f46..f1a38d20f39 100644
--- a/lisp/obsolete/terminal.el
+++ b/lisp/obsolete/terminal.el
@@ -291,7 +291,9 @@ Other chars following \"%s\" are interpreted as follows:\n"
 ;; not used.
 (defun te-escape-extended-command-unread ()
   (interactive)
-  (setq unread-command-events (listify-key-sequence (this-command-keys)))
+  (setq unread-command-events
+        (nconc (listify-key-sequence (this-command-keys))
+               unread-command-events))
   (te-escape-extended-command))
 
 (defun te-set-escape-char (c)
diff --git a/lisp/obsolete/vip.el b/lisp/obsolete/vip.el
index d6adbd4d421..0c345e26f80 100644
--- a/lisp/obsolete/vip.el
+++ b/lisp/obsolete/vip.el
@@ -462,7 +462,8 @@ ARG is used as the prefix value for the executed command.  If
 EVENTS is a list of events, which become the beginning of the command."
   (interactive "P")
   (let (com key (old-map (current-local-map)))
-    (if events (setq unread-command-events events))
+    (if events (setq unread-command-events
+                     (append events unread-command-events)))
     (setq prefix-arg arg)
     (use-local-map vip-emacs-local-map)
     (unwind-protect
@@ -518,7 +519,7 @@ obtained so far, and COM is the command part obtained so far."
   (while (= char ?U)
     (vip-describe-arg prefix-arg)
     (setq char (read-char)))
-  (setq unread-command-events (list char)))
+  (push char unread-command-events))
 
 (defun vip-prefix-arg-com (char value com)
   "Vi operator as prefix argument."
@@ -572,7 +573,7 @@ obtained so far, and COM is the command part obtained so far."
         (while (= char ?U)
           (vip-describe-arg prefix-arg)
           (setq char (read-char)))
-        (setq unread-command-events (list char)))
+        (push char unread-command-events))
     ;; as com is non-nil, this means that we have a command to execute
     (if (or (= (car com) ?r) (= (car com) ?R))
         ;; execute appropriate region command.
diff --git a/lisp/pcomplete.el b/lisp/pcomplete.el
index 7bcf2c1759e..90f06953183 100644
--- a/lisp/pcomplete.el
+++ b/lisp/pcomplete.el
@@ -1112,7 +1112,7 @@ Typing SPC flushes the help buffer."
                     (scroll-up))))
               (message ""))
              (t
-              (setq unread-command-events (list event))
+              (push event unread-command-events)
               (throw 'done nil)))))
       (if (and pcomplete-last-window-config
                pcomplete-restore-window-delay)
diff --git a/lisp/progmodes/cperl-mode.el b/lisp/progmodes/cperl-mode.el
index 7d2f3fcb007..826b3ee73a8 100644
--- a/lisp/progmodes/cperl-mode.el
+++ b/lisp/progmodes/cperl-mode.el
@@ -1042,11 +1042,11 @@ In regular expressions (including character classes):
   cperl-can-font-lock)
 
 (defun cperl-putback-char (c)           ; Emacs 19
-  (set 'unread-command-events (list c))) ; Avoid undefined warning
+  (push c unread-command-events))       ; Avoid undefined warning
 
 (if (featurep 'xemacs)
     (defun cperl-putback-char (c)       ; XEmacs >= 19.12
-      (setq unread-command-events (list (eval '(character-to-event c))))))
+      (push (eval '(character-to-event c)) unread-command-events)))
 
 (or (fboundp 'uncomment-region)
     (defun uncomment-region (beg end)
diff --git a/lisp/progmodes/ebrowse.el b/lisp/progmodes/ebrowse.el
index f91e4a741cc..8d7c8aa0267 100644
--- a/lisp/progmodes/ebrowse.el
+++ b/lisp/progmodes/ebrowse.el
@@ -4223,7 +4223,8 @@ NUMBER-OF-STATIC-VARIABLES:"
                                                     (1+ (point)))))))))
       (unless non-empty
         (error "No tree buffers"))
-      (setf unread-command-events (listify-key-sequence "p"))
+      (setf unread-command-events
+            (nconc (listify-key-sequence "p") unread-command-events))
       (shrink-window-if-larger-than-buffer (selected-window))
       (setq buffer-read-only t))))
 
diff --git a/lisp/progmodes/fortran.el b/lisp/progmodes/fortran.el
index 65aa7454008..83e427da790 100644
--- a/lisp/progmodes/fortran.el
+++ b/lisp/progmodes/fortran.el
@@ -1117,7 +1117,7 @@ See also `fortran-window-create'."
           (message "Type SPC to continue editing.")
           (let ((char (read-event)))
             (or (equal char ?\s)
-                (setq unread-command-events (list char))))))
+                (push char unread-command-events)))))
     (fortran-window-create)))
 
 (defun fortran-split-line ()
diff --git a/lisp/progmodes/octave.el b/lisp/progmodes/octave.el
index 50f888cb9fd..89e0b105223 100644
--- a/lisp/progmodes/octave.el
+++ b/lisp/progmodes/octave.el
@@ -919,7 +919,7 @@ startup file, `~/.emacs-octave'."
       (let ((ch (read-event)))
         (if (eq ch ?\ )
             (set-window-configuration conf)
-          (setq unread-command-events (list ch)))))))
+          (push ch unread-command-events))))))
 
 (defun inferior-octave-output-digest (_proc string)
   "Special output filter for the inferior Octave process.
diff --git a/lisp/progmodes/vhdl-mode.el b/lisp/progmodes/vhdl-mode.el
index 16e4e8ed53d..2edacf4e69a 100644
--- a/lisp/progmodes/vhdl-mode.el
+++ b/lisp/progmodes/vhdl-mode.el
@@ -8734,10 +8734,11 @@ is omitted or nil."
                   (let ((next-input (read-char)))
                     (if (= next-input ?-) ; four dashes
                         (vhdl-comment-display t)
-                      (setq unread-command-events ; pushback the char
-                            (list (vhdl-character-to-event next-input))))))
-              (setq unread-command-events ; pushback the char
-                    (list (vhdl-character-to-event next-input)))
+                      (push (vhdl-character-to-event next-input)
+                                        ; pushback the char
+                            unread-command-events))))
+              (push (vhdl-character-to-event next-input) ; pushback the char
+                    unread-command-events)
               (vhdl-comment-insert)))))
     (self-insert-command count)))
 
@@ -10755,8 +10756,8 @@ If starting after end-comment-column, start a new line."
         (setq code t))
       (unless code
         (insert "--")) ; hardwire to 1 space or use vhdl-basic-offset?
-      (setq unread-command-events
-            (list (vhdl-character-to-event next-input)))))) ; pushback the char
+      (push (vhdl-character-to-event next-input) ; pushback the char
+            unread-command-events))))
 
 (defun vhdl-comment-display (&optional line-exists)
   "Add 2 comment lines at the current indent, making a display comment."
@@ -11310,8 +11311,8 @@ but not if inside a comment or quote."
         ;; delete CR which is still in event queue
         (if (fboundp 'enqueue-eval-event)
             (enqueue-eval-event 'delete-char -1)
-          (setq unread-command-events   ; push back a delete char
-                (list (vhdl-character-to-event ?\177))))))))
+          (push (vhdl-character-to-event ?\177) ; push back a delete char
+                unread-command-events))))))
 
 (defun vhdl-template-alias-hook ()
   (vhdl-hooked-abbrev 'vhdl-template-alias))
diff --git a/lisp/simple.el b/lisp/simple.el
index 1a4bcf124db..00c25db07d7 100644
--- a/lisp/simple.el
+++ b/lisp/simple.el
@@ -693,7 +693,8 @@ any other non-digit terminates the character code and is then used as input."))
       (cond ((null translated))
             ((not (integerp translated))
              (setq unread-command-events
-                   (listify-key-sequence (this-single-command-raw-keys))
+                   (nconc (listify-key-sequence (this-single-command-raw-keys))
+                          unread-command-events)
                    done t))
             ((/= (logand translated ?\M-\^@) 0)
              ;; Turn a meta-character into a character with the 0200 bit set.
@@ -713,7 +714,8 @@ any other non-digit terminates the character code and is then used as input."))
              (setq done t))
             ((not first)
              (setq unread-command-events
-                   (listify-key-sequence (this-single-command-raw-keys))
+                   (nconc (listify-key-sequence (this-single-command-raw-keys))
+                          unread-command-events)
                    done t))
             (t (setq code translated
                      done t)))
diff --git a/lisp/subr.el b/lisp/subr.el
index bfdc0ff4a13..3dd87d65617 100644
--- a/lisp/subr.el
+++ b/lisp/subr.el
@@ -2539,7 +2539,8 @@ If MESSAGE is nil, instructions to type EXIT-CHAR are displayed there."
             (or (eq event exit-char)
                 (eq event (event-convert-list exit-char))
                 (setq unread-command-events
-                      (append (this-single-command-raw-keys))))))
+                      (append (this-single-command-raw-keys)
+                              unread-command-events)))))
       (delete-overlay ol))))
 
 
diff --git a/lisp/term.el b/lisp/term.el
index 4c829864200..06a44f29058 100644
--- a/lisp/term.el
+++ b/lisp/term.el
@@ -1649,7 +1649,7 @@ See also `term-read-input-ring'."
       (let ((ch (read-event)))
         (if (eq ch ?\s)
             (set-window-configuration conf)
-          (setq unread-command-events (list ch)))))))
+          (push ch unread-command-events))))))
 
 
 (defun term-regexp-arg (prompt)
@@ -4128,7 +4128,9 @@ Typing SPC flushes the help buffer."
             (set-window-configuration conf))
         (if (eq first ?\s)
             (set-window-configuration conf)
-          (setq unread-command-events (listify-key-sequence key)))))))
+          (setq unread-command-events
+                (nconc (listify-key-sequence key)
+                       unread-command-events)))))))
 
 ;; I need a make-term that doesn't surround with *s -mm
 (defun term-ansi-make-term (name program &optional startfile &rest switches)
diff --git a/lisp/vc/emerge.el b/lisp/vc/emerge.el
index b17d11d34a4..de25cbafb0d 100644
--- a/lisp/vc/emerge.el
+++ b/lisp/vc/emerge.el
@@ -3089,7 +3089,7 @@ SPC, it is ignored; if it is anything else, it is processed as a command."
             (let* ((echo-keystrokes 0)
                    (c (read-event)))
               (if (not (eq c 32))
-                  (setq unread-command-events (list c)))))
+                  (push c unread-command-events))))
         (erase-buffer)))))
 
 ;; Improved auto-save file names.