Subject: Support git in ediff-patch-file

From: Juri Linkov <[email-masked]>
Date: Thu, 25 Apr 2019 00:38:43 +0300

This patch adds support for git patches to ediff-patch-file:

diff --git a/lisp/vc/ediff-ptch.el b/lisp/vc/ediff-ptch.el
index 4178b5a8c0..5c71c2c8cb 100644
--- a/lisp/vc/ediff-ptch.el
+++ b/lisp/vc/ediff-ptch.el
@@ -297,11 +297,15 @@ ediff-fixup-patch-map
 	      ;; 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 "")
+		    (when (and (string-match-p "^a/" base-dir1)
+			       (string-match-p "^b/" base-dir2))
+		      (setq base-dir1 "a/"
+			    base-dir2 "b/")))))
 	      (or (string= (car proposed-file-names) "/dev/null")
 		  (setcar proposed-file-names
 			  (ediff-file-name-sans-prefix