The different favicon introduced here : http://bugs.koha-community.org/bugzilla3/show_bug.cgi?id=7949 is only showing in the english interface it seems. My guess is that the translation machinery is not picking it up. Also the favicon is located in a language specific folder, it could be higher up in the hierarchy, with other images.
I can't reproduce this bug with a freshly generated set of fr-FR templates.
I still can't reproduce this. If you're still having this problem and can provide more details, please re-open.