Add tests for issue #4460

* subversion/tests/cmdline/diff_tests.py
  (diff_repo_wc_file_props, diff_repo_repo_added_file_mime_type, test_list):
    Add new tests.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1563066 13f79535-47bb-0310-9956-ffa450edef68