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

== New Features ==

 * `hg mv -A` can now be used with `--at-rev`. It behaves just like
   `hg cp -A --at-rev`, i.e. it marks the destination as a copy of the
   source whether or not the source still exists (but the source must
   exist in the parent revision).


== New Experimental Features ==



== Bug Fixes ==



== Backwards Compatibility Changes ==



== Internal API Changes ==