tests/test-gendoc-ru.t

copies: avoid materializing a full directory map during copy tracing

Materializing a full copy of every directory in a treemanifest repo can be quite
expensive, even with a narrow matcher. For flat manifest repos, this should be
equivalent - it will still materialize (and cache) a dict of all of the dirs
inside of the manifest object, we just don't get a copy of it.

In a repo I have here, this brings the time for a simple rebase from 11.197s to
4.609s.

Differential Revision: https://phab.mercurial-scm.org/D9503

#require docutils gettext

  $ $TESTDIR/check-gendoc ru
  checking for parse errors