Add another helper method to the testing sandbox.
Add another helper method to the testing sandbox.

* subversion/tests/cmdline/svntest/sandbox.py:
  (Sandbox.simple_update): New method.


git-svn-id: f8a4e5e023278da1e04e203c7fe051e3c4285d88@984765 13f79535-47bb-0310-9956-ffa450edef68

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