The same problem occurs on fr.wikibooks, fr.wikiversity, and fr.wikinews, whereas on the other French projects it works.

This is probably because these wikis (frwikiquote, frwikibooks, frwikiversity, frwikinews) have no entries in $wmgBabelCategoryNames.

Are there a community discussions on this problem(?) indicating that there should be categories?

Not recently, but these categories had been created for years, and nobody planned to delete them.

http://fr.wikiquote.org/wiki/Cat%C3%A9gorie:Utilisateurs_par_langue
http://fr.wikibooks.org/wiki/Cat%C3%A9gorie:Utilisateurs_par_langue
http://fr.wikiversity.org/wiki/Cat%C3%A9gorie:Utilisateurs_par_langues
http://fr.wikinews.org/wiki/Cat%C3%A9gorie:Utilisateur_par_langue

Discussion page:
https://fr.wikiquote.org/wiki/Wikiquote:Le_Salon/septembre_2012#Configuration_Babel

Taking this bug. Gerrit change 23076.

Please open 3 other bugs for frwikibooks, frwikiversity and frwikinews.

The Gerrit change returns
Application Error
The page you requested was not found, or you do not have permission to view this page.

The process you've exposed doesn't seem to be normal, is there a consensus about it?

Actually the Babel extension has been deployed on all the foundation wikis, which is an invitation to use it, even more as it's more practical than our old templates. Templates which are still on fr.wikiquote, frwikibooks, frwikiversity and frwikinews.

So as its categories had been properly configured without any consensus on fr.wiktionary for example, it should be done everywhere as well. Otherwise the users may fall in this trap like I did, by using an unconfigured validated extension.

Gerrit. Yes, we've a Gerrit issue, drafts aren't public in application interface but are available on Gitweb. I'm publishing the config change if you wish.

Local consensus. Every configuration request should get a local consensus. We can make exception for inactive wikis at our discretion. But fr.wikiquote has a community, so you're responsible to discuss any configuration change you want there. This process allows everybody to make comments. Of course, for a trivial config change, a full prise de décision isn't needed. An informal discussion on the salon (which is your village pump) seems enough to be (but ultimately, it's up to your community to define what is acceptable or not as process to get local consensus).

Precedents. I personally previously handled bug #37401 (Siebrand approval for fo.) and bug #37981 (explicit no active community mention in the bug).

Babel deployment. The feature isn't really known by the users, so as long as a wiki doesn't use it/document it, this is not an issue.

[ shellpolicy -> shell ]

The issue has been publicized more than 2 weeks on the local village pump and received no objection.

I discussed the issue with experienced French projects contributors, among them Linedwell, who also followed the Babel extension deployment, and we have the feeling a non controversial change, following years of userboxes practices, with notification and no objection does constitute a local consensus.

Merged by Reedy.