Comment 10 for bug 732768

That is not the right way to work around it and it might cause future problems for people who follow your workaround.

The only workaround I recommend is to remove the empty /usr/lib/firefox-addons/searchplugins/$(LANGUAGE) folder for your locale (eg, /usr/lib/firefox-addons/searchplugins/en-GB if you are using en-GB). This will trick Firefox in to using the fallback en-US searchplugins which it provides independently of the language packs, and will ensure that your system is restored to the intended state once the language packs are fixed.