Add a regression test for some stupid user errors that might break the working
copy if we don't detect them.

* subversion/tests/cmdline/input_validation_tests.py
  (delete_repos_root): New test.
  (test_list): Add test.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1444238 13f79535-47bb-0310-9956-ffa450edef68