rename: add support for --at-rev, which marks as copy and removes the source
I had previously only added support for `--at-rev` to `hg cp`, but not
to `hg mv`. This patch adds that support. Just like for `hg cp`, it
marks the destination as copied from the source, and doesn't care if
the source file still exists (because it only supports the `-A` mode,
aka "don't touch files" mode). It works whether or not the source file
still exists. This matches the behavior of `hg mv -A` in the working
copy.
Differential Revision: https://phab.mercurial-scm.org/D8840
To run the tests, do:
cd tests/
python run-tests.py
See https://mercurial-scm.org/wiki/WritingTests for
more information on writing tests.