epatch: Save right backups in Git multipatches

Multipatches on N Git files save wrong backups for
N-1 files; only the last one has a correct backup (Bug#26084).
* lisp/vc/diff-mode.el (diff-file-junk-re): Add 'Prereq: '
* lisp/vc/ediff-ptch.el (ediff-map-patch-buffer): Use 'diff-file-junk-re'.
* test/lisp/vc/ediff-ptch-tests.el (ediff-ptch-test-bug25010):
Rename from ibuffer-test-bug25010.
(ediff-ptch-test-bug26084): New test.

2 files changed, 7 insertions, 8 deletions

diff --git a/lisp/vc/diff-mode.el b/lisp/vc/diff-mode.el
index 31c33e6a720..aa8d77882ec 100644
--- a/lisp/vc/diff-mode.el
+++ b/lisp/vc/diff-mode.el
@@ -504,7 +504,7 @@ See http://lists.gnu.org/archive/html/emacs-devel/2007-11/msg01990.html")
 ;; "index ", "old mode", "new mode", "new file mode" and
 ;; "deleted file mode" are output by git-diff.
 (defconst diff-file-junk-re
-  (concat "Index: \\|=\\{20,\\}\\|" ; SVN
+  (concat "Index: \\|Prereq: \\|=\\{20,\\}\\|" ; SVN
           "diff \\|index \\|\\(?:deleted file\\|new\\(?: file\\)?\\|old\\) mode\\|=== modified file"))
 
 ;; If point is in a diff header, then return beginning
diff --git a/lisp/vc/ediff-ptch.el b/lisp/vc/ediff-ptch.el
index 9d2ec51b596..36aebf4aed1 100644
--- a/lisp/vc/ediff-ptch.el
+++ b/lisp/vc/ediff-ptch.el
@@ -25,6 +25,8 @@
 ;;; Code:
 
 
+(require 'diff-mode) ; For `diff-file-junk-re'.
+
 (provide 'ediff-ptch)
 
 (defgroup ediff-ptch nil
@@ -225,14 +227,11 @@ program."
                         (if (and beg2 end2)
                             (buffer-substring beg2 end2)
                           "/dev/null")))
-            ;; check for any `Index:' or `Prereq:' lines, but don't use them
-            (if (re-search-backward "^Index:" mark1-end 'noerror)
-                (move-marker mark2 (match-beginning 0)))
-            (if (re-search-backward "^Prereq:" mark1-end 'noerror)
-                (move-marker mark2 (match-beginning 0)))
-
+            ;; Remove file junk (Bug#26084).
+            (while (re-search-backward
+                    (concat "^" diff-file-junk-re) mark1-end t)
+                (move-marker mark2 (match-beginning 0)))
             (goto-char mark2-end)
-
             (if filenames
                 (setq patch-map
                       (cons (ediff-make-new-meta-list-element