UserAgent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/53.0.2785.116 Safari/537.36

Steps to reproduce the problem:
Some sites, live DeviantArt.com, have one subdomain per user, with that user's portfolio/blog/etc being on that subdomain.

What is the expected behavior?

What went wrong?
If you go to that subdomain while logged out and try to log in, remembered logins for other DeviantArt.com subdmains won't apply.

Did this work before? No 

Chrome version: 53.0.2785.116  Channel: stable
OS Version: Fedora 24
Flash Version: Shockwave Flash 23.0 r0

Sort of related to bug 173459