1 files changed, 39 insertions, 26 deletions

diff --git a/lisp/international/mule.el b/lisp/international/mule.el
index 66e82575ec4..9eeeb30d659 100644
--- a/lisp/international/mule.el
+++ b/lisp/international/mule.el
@@ -728,30 +728,27 @@ The local variable `buffer-file-coding-system' of the current buffer
 is set to the returned value.
 Return nil if there's no need of setting new buffer-file-coding-system."
   (let (local-coding local-eol
-        found-eol
+        found-coding found-eol
         new-coding new-eol)
     (if (null coding)
         ;; Nothing found about coding.
         nil
 
-      ;; Get information of the current local value of
-      ;; `buffer-file-coding-system' in LOCAL-EOL and LOCAL-CODING.
-      (if (local-variable-p 'buffer-file-coding-system)
-          ;; Something already set locally.
-          (progn
-            (setq local-eol (coding-system-eol-type buffer-file-coding-system))
-            (if (null (numberp local-eol))
-                ;; But eol-type is not yet set.
-                (setq local-eol nil))
-            (if (null (eq (coding-system-type buffer-file-coding-system) t))
-                ;; This is not `undecided'.
-                (progn
-                  (setq local-coding buffer-file-coding-system)
-                  (while (symbolp (get local-coding 'coding-system))
-                    (setq local-coding (get local-coding 'coding-system))))
-              )))
-
-      (if (and local-eol local-coding)
+      ;; Get information of `buffer-file-coding-system' in LOCAL-EOL
+      ;; and LOCAL-CODING.
+      (setq local-eol (coding-system-eol-type buffer-file-coding-system))
+      (if (null (numberp local-eol))
+          ;; But eol-type is not yet set.
+          (setq local-eol nil))
+      (when (and buffer-file-coding-system
+                 (not (eq (coding-system-type buffer-file-coding-system) t)))
+        ;; This is not `undecided'.
+        (setq local-coding buffer-file-coding-system)
+        (while (symbolp (get local-coding 'coding-system))
+          (setq local-coding (get local-coding 'coding-system))))
+
+      (if (and (local-variable-p 'buffer-file-coding-system)
+               local-eol local-coding)
           ;; The current buffer has already set full coding-system, we
           ;; had better not change it.
           nil
@@ -760,15 +757,31 @@ Return nil if there's no need of setting new buffer-file-coding-system."
         (if (null (numberp found-eol))
             ;; But eol-type is not found.
             (setq found-eol nil))
+        (unless (eq (coding-system-type coding) t)
+          ;; This is not `undecided'.
+          (setq found-coding coding)
+          (while (symbolp (get found-coding 'coding-system))
+            (setq found-coding (get found-coding 'coding-system))))
 
         ;; The local setting takes precedence over the found one.
-        (setq new-coding (or local-coding coding))
-        (setq new-eol (or local-eol found-eol))
-        (if (and (numberp new-eol)
-                 (vectorp (coding-system-eol-type new-coding)))
-            (setq new-coding
-                  (aref (coding-system-eol-type new-coding) new-eol)))
-        new-coding))))
+        (setq new-coding (or (and (local-variable-p 'buffer-file-coding-system)
+                                  local-coding)
+                             found-coding
+                             local-coding))
+        (setq new-eol (or (and (local-variable-p 'buffer-file-coding-system)
+                               local-eol)
+                          found-eol
+                          local-eol))
+        (when (numberp new-eol)
+          (or new-coding
+              (setq new-coding 'undecided))
+          (if (vectorp (coding-system-eol-type new-coding))
+              (setq new-coding
+                    (aref (coding-system-eol-type new-coding) new-eol))))
+        ;; Return a new coding system only when it is different from
+        ;; the current one.
+        (if (not (eq buffer-file-coding-system new-coding))
+            new-coding)))))
 
 (defun modify-coding-system-alist (target-type regexp coding-system)
   "Modify one of look up tables for finding a coding system on I/O operation.