libreoffice spams stdout with "Fontconfig warning: ignoring C.UTF-8: not a valid language tag"

[sds]

when libreoffice is started from the shell command line, it spams the terminal window with a stream of messages
"Fontconfig warning: ignoring C.UTF-8: not a valid language tag"
This message should be reported at most once per libreoffice invocation.

ProblemType: Bug
DistroRelease: Ubuntu 12.10
Package: fontconfig 2.10.1-0ubuntu3
ProcVersionSignature: Ubuntu 3.5.0-26.42-generic 3.5.7.6
Uname: Linux 3.5.0-26-generic x86_64
ApportVersion: 2.6.1-0ubuntu10
Architecture: amd64
Date: Wed Apr 3 14:22:46 2013
InstallationDate: Installed on 2011-11-01 (519 days ago)
InstallationMedia: Ubuntu 11.10 "Oneiric Ocelot" - Release amd64 (20111012)
MarkForUpload: True
SourcePackage: fontconfig
UpgradeStatus: Upgraded to quantal on 2013-03-21 (12 days ago)

[Mike Gerow (gerow)]

Facing the same issue. According to <https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=717423> this has been fixed in fontconfig=2.11.0-2

[João Manuel Rodrigues (jmr)]

I confirm this on a up-to-date ubuntu 14.04 amd64 server installation. My X server is running on a different machine.

Running gnome-terminal gives:
Fontconfig warning: ignoring C.UTF-8: not a valid language tag

Maybe I could change locale settings to workaround this, but it is bug and there seems to be a fix available.

$ locale
LANG=C.UTF-8
LANGUAGE=
LC_CTYPE="C.UTF-8"
LC_NUMERIC=pt_PT.UTF-8
LC_TIME=pt_PT.UTF-8
LC_COLLATE="C.UTF-8"
LC_MONETARY=pt_PT.UTF-8
LC_MESSAGES="C.UTF-8"
LC_PAPER=pt_PT.UTF-8
LC_NAME=pt_PT.UTF-8
LC_ADDRESS=pt_PT.UTF-8
LC_TELEPHONE=pt_PT.UTF-8
LC_MEASUREMENT=pt_PT.UTF-8
LC_IDENTIFICATION=pt_PT.UTF-8
LC_ALL=

[Margarita Manterola (marga-9)]

This was fixed in Debian, and the fix was integrated into the utopic version:

fontconfig (2.11.1-0ubuntu3) utopic; urgency=medium

  * Merge from Debian 2.11.0-2:
    - 03_locale_c.utf8.patch: based on a patch from Martin Dickopp. Treat
      C.UTF-8 and C.utf8 locales as built in the C library.
      Closes: #717423.

 -- Martin Pitt <email address hidden> Tue, 24 Jun 2014 16:32:49 +0200

But Trusty is still affected.

Any chance this can get integrated into the trusty version?