Wikimedia Bugzilla is closed!

It is the same bug like here: https://bugzilla.wikimedia.org/show_bug.cgi?id=11428

The old bug was not fixed correctly because the block "if( $path == $wgScript ) return;" was added in the function interpolateTitle(). But if api.php is used path is /w/api.php and wgScript is /w/index.php so for the api interpolateTitle() continues.

Patch - Replace line 86 in WebRequest.php with:

                    if(strpos($path, "$wgScriptPath/") === 0 ) {
                        // Script inside a rewrite path?
                        // Abort to keep from breaking...
                        return;
                    }