Bug overview description.
Index: Sorting artists by post count doesn't seem to work, sorting by name instead:

https://e621.net/artist?order=posts

What part(s) of the site page(s) are affected?
Artist page

What is the expected behavior?
Artist page should be sortable by post count.

What actual behavior is given instead?
Artist page is sorted by name.

Time of incident. (If applicable)
N/A

Can you reproduce the bug every time?
Yes

What steps did you take to replicated this bug?
N/A

Errors or other messages returned. (If any)
N/A