bug#41114: 28.0.50; default-directory & buffer-file-name set to file:// URLs

[Tassilo Horn]

1. emacs -Q
2. (browse-url-emacs "file:///home/horn/.bashrc") ;; Adapt file name.

The result of the procedure is that `buffer-file-name' is
"file:///home/horn/.bashrc" and `default-directory' is
"file:///home/horn/".

According to the docs, both variables should be absolute file names, not
URLs.

The problems with those URLs are at least that:

- C-x C-f in that buffer will offer a completely broken initial
  directory when querying for a file or directory.  For me it is
  ~/Repos/el/emacs/src/file:/home/horn/file:/home/horn/.

- When call-process is called from that buffer it'll error that
  file:///home/horn/ cannot be set as current directory.


In GNU Emacs 28.0.50 (build 4, x86_64-pc-linux-gnu, GTK+ Version 3.24.20, cairo 
version 1.17.3)
 of 2020-05-06 built on thinkpad-t440p
Repository revision: 86fef6ab89ee54c6f78bc2064e55c5439e929827
Repository branch: master
Windowing system distributor 'The X.Org Foundation', version 11.0.12008000
System Description: Arch Linux

Recent messages:
20200506T231237.545> nnimap read 0k from imap.fastmail.com
20200506T231240.944> Exiting summary buffer and applying spam rules
20200506T231240.963> Expiring articles...
20200506T231241.412> Expiring articles...done
20200506T231242.815> Saving Gnus registry (5077 entries) to 
~/.gnus.d/.gnus.registry.eieio...
20200506T231243.315> Saving Gnus registry (size 5077) to 
~/.gnus.d/.gnus.registry.eieio...done
20200506T231243.316> Saving /home/horn/.gnus.d/.newsrc.eld...
Saving file /home/horn/.gnus.d/.newsrc.eld...
Wrote /home/horn/.gnus.d/.newsrc.eld
20200506T231243.332> Saving /home/horn/.gnus.d/.newsrc.eld...done

Configured using:
 'configure --with-modules --with-cairo'

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

Important settings:
  value of $LC_MONETARY: de_DE.utf8
  value of $LC_NUMERIC: de_DE.utf8
  value of $LC_TIME: de_DE.utf8
  value of $LANG: en_US.utf8
  value of $XMODIFIERS: @im=ibus
  locale-coding-system: utf-8-unix

Major mode: Lisp Interaction

Minor modes in effect:
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  global-git-commit-mode: t
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  override-global-mode: t
  minibuffer-depth-indicate-mode: t
  electric-pair-mode: t
  recentf-mode: t
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  save-place-mode: t
  savehist-mode: t
  show-paren-mode: t
  global-ligature-minor-mode: t
  ligature-minor-mode: t
  shell-dirtrack-mode: t
  tooltip-mode: t
  global-eldoc-mode: t
  eldoc-mode: t
  electric-indent-mode: t
  mouse-wheel-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  column-number-mode: t
  line-number-mode: t
  transient-mark-mode: t

Load-path shadows:
None found.

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