Comment 4 for bug 159589

This makes LockContention include the lock file name in more cases, so
that you get some clue as to what's happening. I reproduced this
earlier while trying to branch from a branch while pushing it. (I
think that in turn is another instance of the shortcomings of
write-locking the dirstate to update the cache while doing a readonly
operation, but giving a better message here will make it more
obvious.)

This includes a bonus fix for the repr of SmartClientStreamMedium; see
the comment.

--
Martin <http://launchpad.net/~mbp/>