Re: The snag with a four-week release cycle ...
Ha ha... Try downloading a file and (when the dialog pops up asking which filename to save to) using a filename with double spaces.
Since time immemorial, file system operations either succeed or not (giving an error message like "cannot save for $reason"). Now Firefox has a third mode of operation, "I'm gonna save the file, but with a different name"... I wonder how it passed their tests.