Aliasing artists to a blank name appears to be nonfunctional

BUR #44108 has been approved by @evazion.

create alias akizuki_(17769498) -> kawanishimaki

BUR #44115 has been approved by @evazion.

create alias akiei -> akiyomi

Both of these fail upon attempting to be accepted. These would previously have been valid. I've been trying to get these unstuck by aliasing them back and forward a few times, creating a new entry for one of the blank tags and renaming but curiously they don't function. Both of these will succeed when the operands are reversed but in their current original state, they fail.

Any insight? Seems like it's just these two tags, since similar-natured aliases can be accepted as below:

BUR #44096 has been approved by @hasu_no_tokimeki.

create alias myv_dr -> miyavi_(myv_dr)

For the two failing ones above, I can't find an original BUR where they were aliased either. Maybe some smithing with unaliases needs to be done to correct these tags.

This has been fixed. The problem was that when a tag is moved it also updates everyone's blacklists, but now there's a limit on the number of blacklisted tags you can have, which caused it to fail because some users were over the limit.

(The limit is 5000 tags, but a few users have tens of thousands of artists blacklisted for no good reason).