MAILBOX_FORMAT_NETNEWS - is it actually needed?

[Bron Gondwana]

I've just been searching through the sourcecode trying to find any
evidence that MAILBOX_FORMAT_NETNEWS actually changes how anything
works.

It looks like it's used in charset_searchfile and charset_extractfile
and asserted in a couple of places that don't seem to make heaps of
sense to me - things like being unable to find the filename for the
file, and not copying the cache record when copying messages between
mailboxes.

Does anyone remember why it's done this way, and if it's still needed?
It would be nice to be able to simplify...

Thanks,

Bron.