Add a test for issue 4102 "error adding symlink to external dir".
Add a test for issue 4102 "error adding symlink to external dir".

* subversion/tests/cmdline/special_tests.py
  (externals_as_symlink_targets): New test.
  (test_list): Add new test.

Found by: Evan Wee <evanw@nationalfibre.net>



git-svn-id: f8a4e5e023278da1e04e203c7fe051e3c4285d88@1233292 13f79535-47bb-0310-9956-ffa450edef68

YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion