Alias warhammer_40000 -> warhammer_40k

BUR #26431 has been rejected.

create alias warhammer_40000 -> warhammer_40k

Utility alias. Same copyright, tag is used elsewhere but much less common.

I don't see how this would help anybody. warhammer 40k is already the top of the tag list when typing "warh" and remains there until "warhammer" because of a warhammer->war hammer alias, and returns to 1st place when you add the underscore. warhammer 40000 should just be an Other Name. Aliases are for names that actually different from the tag name, not the exact same name except for a slight difference at the end.

The bulk update request #26431 (forum #281301) has been rejected by @nonamethanks.