Add an XFail-ing regression text for issue #3390 (Relative externals not updated during switch).
Add an XFail-ing regression text for issue #3390 (Relative externals
not updated during switch).

* subversion/tests/cmdline/externals_tests.py
  (switch_relative_external): New test.
  (test_list): Add reference to new test, XFail'd.


git-svn-id: f8a4e5e023278da1e04e203c7fe051e3c4285d88@877016 13f79535-47bb-0310-9956-ffa450edef68

wbond/subversion,wbond/subversion,wbond/subversion,wbond/subversion,YueLinHo/Subversion,YueLinHo/Subversion,wbond/subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,wbond/subversion,wbond/subversion,YueLinHo/Subversion