Please test Special:FileDuplicateSearch on default ("ugly URL") wikis,
e.g., the URL above. Don't only test just on Wikipedia.

Try even just clicking the button with no string entered.

On wikipedia, this will get one to
http://en.wikipedia.org/wiki/Special:FileDuplicateSearch?filename=
which is fine. But on default path wikis, one ends up at
http://radioscanningtw.jidanni.org/index.php?filename=
i.e., suddenly sent to the Main_Page.

I hope there are no other Special Pages with the same bug.

Version: 1.15.x
Severity: normal
URL: http://radioscanningtw.jidanni.org/index.php?title=Special:FileDuplicateSearch&uselang=en