bug#4417: 23.1.50; vc-hg is broken in non-English locales

[Dan Nicolaescu <dann@ics.uci.edu>]

Sven Joachim <svenjoac@gmx.de> writes:

  > When opening a file in a mercurial-controlled directory, the modeline
  > shows "Hg-0" instead of the revision number in my de_DE.UTF-8 locale.
  > Moreover, after pressing "C-x v l", the *vc-change-log* buffer is
  > unfontified, and standard keys (d, f) do not work there, because hg's
  > output is in German:
  > 
  > ,----
  > | Änderung:        1587:1cdfa7c5503e
  > | Vorgänger:       1585:ef75fa728cca
  > | Nutzer:          Daniel Burrows <dburrows@debian.org>
  > | Datum:           Sun Jul 20 12:31:09 2008 -0700
  > | Zusammenfassung: Document how aptitude handles double-quotes.
  > `----
  > 
  > Setting LANG to C works around the problems.  For the reference, this is
  > my mercurial version:
  > 
  > ,----
  > | % hg --version
  > | Mercurial Distributed SCM (version 1.3.1)
  > `----
  > 
  > In GNU Emacs 23.1.50.6 (i486-pc-linux-gnu, GTK+ Version 2.16.6)
  >  of 2009-09-12 on turtle
  > Windowing system distributor `The X.Org Foundation', version 11.0.10603000
  > configured using `configure  '--build=i486-linux-gnu' 'build_alias=i486-linux-gnu' 'CFLAGS=-DGTK_DISABLE_DEPRECATED -g -O2''

I still cannot reproduce this... but it's not unreasonable that it
happens.

The "Hg-0" problem happens because vc-hg parses the "hg log" output so
that it can get the version number to display in the modeline (in
`vc-hg-working-revision').
I'll check in a fix shortly.

For the C-x v l problem, would it be acceptable for vc-hg to force the
language to be C?  If not, then someone would have to write regexps that
match the  "hg log" entries in any language.