The problem seems to be an error in launchpad po file export function. It turncates the plural definition in a wrong way. So if you reimport a po file, it will break.
-- [update-manager] wrong translation crashes application https://launchpad.net/bugs/63344 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
