[MERGE] Improve "Path(s) are not versioned" error reporting for some commands

[Andrew Bennetts]

Benoît PIERRE wrote:
[...]
> I honestly did not go through the testsuite because even without
> this patch I get quite a few errors and some hangups during
> selftest.

Which platform are you on, and which version of Python?

Is there a bug report of mail with a summary of your selftest errors and
hangs I could look at?

-Andrew.