All F7,F8 and rawhide versions seem to be affected (1.2.12-1.3.6)

Preamble:

There is a wide-spread locale settings, popular for developers, where the LANG
is set according to the true native language (as usual), but LC_MESSAGES is set
to "C" . 

This way programs know the local language and character set properly, but all
the messages for a user are in English (because of "C" locale), not the native
language.


Unfortunately, the Cups code interpretes LC_MESSAGES in some non-standard way.
It tries to determine the WHOLE locale language first just by LC_MESSAGES (not
by LC_ALL or LANG, as it should be). It seems not correct anyway.

In the currect Cups code, if you set in /etc/sysconfig/i18n, say
LANG=de_DE.UTF-8 and LC_MESSAGES=C , the "attributes-natural-languages" appears
to be "c-" broken string. Then the LANG variable in the Cups filters and
backends appears as "c-" too, which leads to leak of locale support at all.

The LANG/LC_MESSAGES combination above is correct. Cups must know the actual
locale language (and choose proper fonts, encodings etc.), but the user/logfile
messages ONLY (diagnostic, info etc.) should be in "C" locale.


Steps to Reproduce:

1. Wrote a shell wrapper around any of /usr/lib/cups/filters/, say texttopaps,
which will output the actual runtime environment

#!/bin/sh

env >>/tmp/env.dump
exec $0.orig "$@"


2. Print something (which will touch the wrapped filter) with the locale
settings described above:

LANG=de_DE.UTF-8 LC_MESSAGES=C lpr some_file


3. In the /tmp/env.dump you will see the "LANG=c-" strange values...

I've made a patch, which seems to fix the issue. See the patch and comments in
it for more info.