bug#25951: 26.0.50; Error when ediffing files that are visited using quoted file names

[Philipp Stephani]

Assuming /tmp/[ab].py are existing files.

emacs -Q -f server-start /:/tmp/a.py

Then:

emacsclient --create-frame --eval '(ediff "/tmp/a.py" "/tmp/b.py")'

will result un an error:

*ERROR*: Wrong type argument: arrayp, nil

Backtrace is

Debugger entered--Lisp error: (wrong-type-argument arrayp nil)
  file-name-non-special(verify-visited-file-modtime #<buffer a.py>)
  verify-visited-file-modtime(#<buffer a.py>)
  apply(verify-visited-file-modtime #<buffer a.py>)
  tramp-run-real-handler(verify-visited-file-modtime (#<buffer a.py>))
  tramp-file-name-handler(verify-visited-file-modtime #<buffer a.py>)
  verify-visited-file-modtime(#<buffer a.py>)
  find-file-noselect("/tmp/a.py")
  ediff-find-file(file-A buf-A ediff-last-dir-A startup-hooks)
  ediff-files-internal("/tmp/a.py" "/tmp/b.py" nil nil ediff-files)
  ediff("/tmp/a.py" "/tmp/b.py")
  eval((ediff "/tmp/a.py" "/tmp/b.py"))
  server-eval-and-print("(ediff \"/tmp/a.py\" \"/tmp/b.py\")" #<process server 
<3>>)
  (more uninteresting frames)



In GNU Emacs 26.0.50 (build 10, x86_64-unknown-linux-gnu, GTK+ Version 3.10.8)
 of 2017-03-03 built on localhost
Repository revision: 244de7b0ed3bb23e700c9edef51e413602d8720a
Windowing system distributor 'The X.Org Foundation', version 11.0.11501000
System Description:     Ubuntu 14.04 LTS

Recent messages:
For information about GNU Emacs and the GNU system, type C-h C-a.

Configured using:
 'configure --enable-checking --enable-check-lisp-object-type
 --with-modules 'CFLAGS=-O0 -ggdb3''

Configured features:
XPM JPEG TIFF GIF PNG SOUND GSETTINGS NOTIFY GNUTLS FREETYPE XFT ZLIB
TOOLKIT_SCROLL_BARS GTK3 X11 MODULES

Important settings:
  value of $LANG: en_US.UTF-8
  locale-coding-system: utf-8-unix

Major mode: Lisp Interaction

Minor modes in effect:
  tooltip-mode: t
  global-eldoc-mode: t
  electric-indent-mode: t
  mouse-wheel-mode: t
  tool-bar-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  blink-cursor-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  line-number-mode: t
  transient-mark-mode: t

Load-path shadows:
None found.

Features:
(shadow sort mail-extr emacsbug message puny seq byte-opt subr-x gv
bytecomp byte-compile cl-extra help-mode cconv cl-loaddefs pcase cl-lib
dired dired-loaddefs format-spec rfc822 mml easymenu mml-sec
password-cache epa derived epg epg-config gnus-util rmail rmail-loaddefs
mm-decode mm-bodies mm-encode mail-parse rfc2231 mailabbrev gmm-utils
mailheader sendmail rfc2047 rfc2045 ietf-drums mm-util mail-prsvr
mail-utils time-date mule-util tooltip eldoc electric uniquify
ediff-hook vc-hooks lisp-float-type mwheel term/x-win x-win
term/common-win x-dnd tool-bar dnd fontset image regexp-opt fringe
tabulated-list replace newcomment text-mode elisp-mode lisp-mode
prog-mode register page menu-bar rfn-eshadow isearch timer select
scroll-bar mouse jit-lock font-lock syntax facemenu font-core
term/tty-colors frame cl-generic cham georgian utf-8-lang misc-lang
vietnamese tibetan thai tai-viet lao korean japanese eucjp-ms cp51932
hebrew greek romanian slovak czech european ethiopic indian cyrillic
chinese composite charscript case-table epa-hook jka-cmpr-hook help
simple abbrev obarray minibuffer cl-preloaded nadvice loaddefs button
faces cus-face macroexp files text-properties overlay sha1 md5 base64
format env code-pages mule custom widget hashtable-print-readable
backquote inotify dynamic-setting system-font-setting
font-render-setting move-toolbar gtk x-toolkit x multi-tty
make-network-process emacs)

Memory information:
((conses 16 96397 9305)
 (symbols 48 20188 1)
 (miscs 40 39 181)
 (strings 32 17669 3597)
 (string-bytes 1 574142)
 (vectors 16 14048)
 (vector-slots 8 483315 4785)
 (floats 8 48 68)
 (intervals 56 217 0)
 (buffers 976 12)
 (heap 1024 19322 1007))

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