The bulk update request #8841 has been rejected.
create alias pony_girl -> pony_play
Without wiki for both tags (the latter can be saved for "Wiki Request" topic), it's unclear what purpose the former tag served with its ambiguous name. While it could mean another tag for horse girl, turns out it's actually an other tag for pony play judging from the past usage, making it redundant no matter what it actually means.
Edit: The second option is we could just nuke it.