What about a file that exists and has just been "add"ed, so it is
technically under version control but no version exists in the
database yet? [Suggest warning, dropping it from the manifest but not
deleting the file. This is the natural (IMO) way to recover from
accidentally adding a file that shouldn't have been added.]
dir exists, but has untracked children and -R is given
dir dropped but not deleted and warning given
I am tempted to request a special case for when every single untracked
child is an ignored file: move the directory into _MTN/trash/ and
print a warning. (I'm not convinced this is a good idea. Talk to
Derek, he was working on recovering from this sort of situation.)