Reading the xxxxxxUserName cookie might be handy on Special:UserLogin for returning users, but autopopulating the username field on Special:UserLogin&type=signup with the credentials of the last logged in user doesn't make any sense and should be removed.
Version: 1.21.x
Severity: normal
Heh, I've noticed this for years, but never bothered filing a bug about it. Thank you. :-)
It would help, generally, if the logic between Special:CreateAccount and Special:UserLogin were (more) distinct (bug 15700).
Userlogin pre-fills the username with your username if you're already logged-in username, or the <site>UserName cookie. I think neither makes sense when creating an account; gerrit 44775 eliminates both.
(In reply to comment #3)
I mean Gerrit change #48071
Merged by Chris S. Marking this bug resolved/fixed.