Make ediff handle remote and quoted file names

Quoted file names need to be unquoted before passed to
subprocesses (Bug#25950).

* lisp/vc/ediff-diff.el (ediff-exec-process): Handle remote and quoted
file names.
* test/lisp/vc/ediff-diff-tests.el
(ediff-diff-tests--ediff-exec-process--quoted-file): Add unit test.

lisp/vc/ediff-diff.el

@@ -1149,7 +1149,11 @@ delimiter regions"))
 	     ediff-coding-system-for-write
 	   ediff-coding-system-for-read))
 	args)
-    (setq args (append (split-string options) files))
+    (setq args (append (split-string options)
+                       (mapcar (lambda (file)
+                                 (file-name-unquote
+                                  (or (file-local-copy file) file)))
+                               files)))
     (setq args (delete "" (delq nil args))) ; delete nil and "" from arguments
     ;; the --binary option, if present, should be used only for buffer jobs
     ;; or for refining the differences

test/lisp/vc/ediff-diff-tests.el

@@ -0,0 +1,44 @@
+;;; ediff-diff-tests.el --- Unit tests for ediff-diff.el  -*- lexical-binding: t; -*-
+
+;; Copyright (C) 2017  Free Software Foundation, Inc.
+
+;; Author: Philipp Stephani <phst@google.com>
+
+;; This file is part of GNU Emacs.
+
+;; GNU Emacs is free software: you can redistribute it and/or modify
+;; it under the terms of the GNU General Public License as published by
+;; the Free Software Foundation, either version 3 of the License, or
+;; (at your option) any later version.
+
+;; GNU Emacs is distributed in the hope that it will be useful,
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;; GNU General Public License for more details.
+
+;; You should have received a copy of the GNU General Public License
+;; along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.
+
+;;; Commentary:
+
+;; Unit tests for lisp/vc/ediff-diff.el.
+
+;;; Code:
+
+(require 'ediff-diff)
+
+(require 'cl-lib)
+(require 'ert)
+
+(ert-deftest ediff-diff-tests--ediff-exec-process--quoted-file ()
+  "Check that Bug#25950 is fixed."
+  (cl-letf* ((call-process-args ())
+             ((symbol-function #'call-process)
+              (lambda (&rest args) (push args call-process-args) 0)))
+    (with-temp-buffer
+      (ediff-exec-process "diff" (current-buffer) :synchronous ""
+                          "/:/a" "/:/b")
+      (should (equal call-process-args
+                     `(("diff" nil ,(current-buffer) nil "/a" "/b")))))))
+
+;;; ediff-diff-tests.el ends here