Last modified: 2013-09-04 11:51:39 UTC
Special:SpecialPages always uses specialpagesgroup-login as the group name the message displayed is "Login / sign up" If $wgUser->isAllowed( 'createaccount' ) = false; Special:SpecialPages should display "Login". The title for the login page as displayed by Special:SpecialPages has the same issue.
Note: the last sentence is bug 19186 and has already been fixed.