We should find filenamess with characters that are illegal on some platforms, and complain.
Enhancements which don't currently have patches on them which are targetted at 2.18 are being retargetted to 2.20 because we're about to freeze for 2.18. Consideration will be taken for moving items back to 2.18 on a case-by-case basis (but is unlikely for enhancements)
Bugzilla 2.20 feature set is now frozen as of 15 Sept 2004. Anything flagged enhancement that hasn't already landed is being pushed out. If this bug is otherwise ready to land, we'll handle it on a case-by-case basis, please set the blocking2.20 flag to '?' if you think it qualifies.
I don't think there is any need for this. New files must be approved by a reviewer and an approver. I doubt an invalid file name will ever pass through.