Last modified: 2012-06-21 20:44:42 UTC
The CustomUserSignup extension (<https://www.mediawiki.org/wiki/Extension:CustomUserSignup>) seems to break the "Log in" link when there is no title parameter specified in the URL. For example, when I visit <https://en.wikipedia.org/w/index.php?diff=487091089&oldid=485846286> and click "Log in" in the top right-hand corner, I'm directed to <https://en.wikipedia.org/wiki/Special:UserLogin&campaign=ACP3>, which is an invalid URL construct. However, if a title parameter is specified, the "Log in" link directs me to <https://en.wikipedia.org/w/index.php?title=Special:UserLogin&returnto=Main+Page&returntoquery=diff%3D487091089%26oldid%3D485846286>, which is a valid URL construct.