I tried to reproduce this and couldn't, but this is consistent with the
hypothesis that it is a problem of unsynchronized simultaneous access to the
global cache.  (Such a problem would be hard to reproduce on demand.)

I did, however, capture the entire state of my global cache and the two
repositories after it happened...  Here, I will attach that state to this ticket.

Oh!  It happened again.  Yes, I am able to reproduce this *some* of the time by
doing a darcs get from the "tailored" repo while tailor is busy updating the
working directory of that repo and invoking 'darcs record' in that repo.