[Unison-hackers] Treat directory as atomic?

[Ryan Newton]

It would be great to be able to add patterns to an "atomic" list.
Something on the atomic list would be treated as a leaf of
synchronization even if it is a directory.

There are many examples of directories that should be treated
atomically: for example, the fsfs database for my subversion
repository.  Or, on the Macintosh, by convention many "files" are
represented by directories -- such as keynote presentations (.key).

Any ideas?  Apologies if I've missed some way to do this with the
current options.  If someone wise could give me a bit of high-level
advice on how to implement this feature, I could maybe give it a shot.

Cheers,
-Ryan