bug#34202: 27.0.50; Opening a pdf shows raw file at first

[Marcin Borkowski]

`C-x C-f' any pdf file.  What is shown is a raw view instead of rendered
pdf.  After e.g. pressing an arrow or `n', docview (or pdf-tools if
installed) kicks in correctly.  Tested on emacs -Q.


In GNU Emacs 27.0.50 (build 16, x86_64-pc-linux-gnu, GTK+ Version 3.24.3)
 of 2019-01-24 built on tars
Repository revision: 0744c35307d544d960c9d7628ea91ad722ff6217
Repository branch: master
Windowing system distributor 'The X.Org Foundation', version 11.0.12003000
System Description: Arch Linux

Configured using:
 'configure --with-xwidgets --with-xaw3d'

Configured features:
XPM JPEG TIFF GIF PNG RSVG IMAGEMAGICK SOUND GPM DBUS GSETTINGS GLIB
NOTIFY INOTIFY ACL GNUTLS LIBXML2 FREETYPE M17N_FLT LIBOTF XFT ZLIB
TOOLKIT_SCROLL_BARS GTK3 X11 XDBE XIM THREADS XWIDGETS LIBSYSTEMD JSON
CANNOT_DUMP LCMS2 GMP

Important settings:
  value of $LC_COLLATE: pl_PL.UTF-8
  value of $LC_CTYPE: pl_PL.UTF-8
  value of $LC_MESSAGES: en_US.UTF-8
  value of $LC_MONETARY: pl_PL.UTF-8
  value of $LC_NUMERIC: en_US.UTF-8
  value of $LC_TIME: pl_PL.UTF-8
  value of $LANG: en_US.UTF-8
  locale-coding-system: utf-8-unix

--
Marcin Borkowski
http://mbork.pl