Fix some tests that assume they can use global resource and then
fail miserably in parallel-test mode.

* subversion/tests/cmdline/relocate_tests.py
  (relocate_and_propset, single_file_relocate):
   Don't touch svntest.main.greek_dump_dir; it's a global directory and
   fiddling with it may lead to races and spurious test failures
   in parallel mode.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1620274 13f79535-47bb-0310-9956-ffa450edef68