Following up on r37368, check ra libraries instead of the url. This resolves an incompatibility with the python versions on the buildbots.
Following up on r37368, check ra libraries instead of the url. This
resolves an incompatibility with the python versions on the buildbots.

* subversion/tests/cmdline/merge_tests.py
  (imports): Import is_ra_type_dav and is_ra_type_svn.
  (merge_fails_if_subtree_is_deleted_on_src): Check ra type instead of url.

jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion