[Mimedefang] BUG: filter_bad_filename doesn't expect a space

[Jay Levitt]

David Skoll wrote (and Chris Myers concurred):

> That's a feature, not a bug. :-)  Consider these two malformed MIME
headers:
>
> Content-Disposition: attachment; filename=test.com example.txt
> Content-Disposition: attachment; filename=example.txt test.com

Ah, good point!  I'm a RE novice, but is there a way to craft a RE that will
disallow the above because it's not quoted, but will allow a properly
formed, quoted filename with a space in it?  (Saying "no" will only force me
to read through Mastering Regular Expressions tonight and prove you wrong
with some brilliant yet entirely incomprehensible solution.. but then, that
pretty much describes any RE in the first place.)

Jay