Our Redis set is only supposed to include pages in the main namespace (and thus ignores category changes to other pages).

However, it should listen to cross-namespace moves, and remove/add pages as appropriately. Otherwise:

• Pages that are moved into the main namespace will not be added if they have the relevant categories at move-time (this probably affects drafts)
• Pages moved out will clutter the Redis sets (probably more of an edge case)

Version: master
Severity: normal