1 files changed, 22 insertions, 9 deletions

diff --git a/lisp/vc/ediff-ptch.el b/lisp/vc/ediff-ptch.el
index 4178b5a8c05..70c03b5c013 100644
--- a/lisp/vc/ediff-ptch.el
+++ b/lisp/vc/ediff-ptch.el
@@ -297,11 +297,24 @@ program."
               ;; file names. This is a heuristic intended to improve guessing
               (let ((default-directory (file-name-directory filename)))
                 (unless (or (file-name-absolute-p base-dir1)
-                            (file-name-absolute-p base-dir2)
-                            (not (file-exists-p base-dir1))
-                            (not (file-exists-p base-dir2)))
-                  (setq base-dir1 ""
-                        base-dir2 "")))
+                            (file-name-absolute-p base-dir2))
+                  (if (and (file-exists-p base-dir1)
+                           (file-exists-p base-dir2))
+                      (setq base-dir1 ""
+                            base-dir2 "")
+                    ;; Strip possible source/destination prefixes
+                    ;; such as a/ and b/ from dir names.
+                    (save-match-data
+                      (let ((m1 (when (string-match "^[^/]+/" base-dir1)
+                                  (cons (substring base-dir1 0 (match-end 0))
+                                        (substring base-dir1 (match-end 0)))))
+                            (m2 (when (string-match "^[^/]+/" base-dir2)
+                                  (cons (substring base-dir2 0 (match-end 0))
+                                        (substring base-dir2 (match-end 0))))))
+                        (when (and (file-exists-p (cdr m1))
+                                   (file-exists-p (cdr m2)))
+                          (setq base-dir1 (car m1)
+                                base-dir2 (car m2))))))))
               (or (string= (car proposed-file-names) "/dev/null")
                   (setcar proposed-file-names
                           (ediff-file-name-sans-prefix
@@ -325,8 +338,8 @@ program."
     (mapc (lambda (session-info)
             (let ((proposed-file-names
                    (ediff-get-session-objA-name session-info)))
-              (if (and (string-match "^/null/" (car proposed-file-names))
-                       (string-match "^/null/" (cdr proposed-file-names)))
+              (if (and (string-match-p "^/null/" (car proposed-file-names))
+                       (string-match-p "^/null/" (cdr proposed-file-names)))
                   ;; couldn't intuit the file name to patch, so
                   ;; something is amiss
                   (progn
@@ -574,7 +587,7 @@ optional argument, then use it."
         (ediff-patch-file-internal
          patch-buf
          (if (and ediff-patch-map
-                  (not (string-match
+                  (not (string-match-p
                         "^/dev/null"
                         ;; this is the file to patch
                         (ediff-get-session-objA-name (car ediff-patch-map))))
@@ -677,7 +690,7 @@ optional argument, then use it."
          target-buf buf-to-patch file-name-magic-p
          patch-return-code ctl-buf backup-style aux-wind)
 
-    (if (string-match "V" ediff-patch-options)
+    (if (string-match-p "V" ediff-patch-options)
         (error
          "Ediff doesn't take the -V option in `ediff-patch-options'--sorry"))