capplets-data: french warning messages during postinstall configure

[Justin Pryzby]

Upgrading from 1:2.12.3-2 1:2.14.2-1 produced a ton of messages; so
many that I had to background the process and ps aux to figure out
what package was causing them, because my scrollback buffer didn't go
back sufficiently far.  I can't reproduce it now, though...  Anyone
have an old version who can get a "script" typescript of the upgrade,
or dpkg-repack it and make it available.