[PATCH] copy_tests: verify the results of a repos_to_repos copy

In going through the copy tests, I found a test where we copy between
two locations in the repository, but never actually check to see if the
copy worked. This patch adds such a check.

-Hyrum

[[[
* subversion/tests/cmdline/copy_tests.py
  (copy_to_root):
    After doing a repo->repo copy, update the working copy and verify
    that the copy actually happened.
]]]