Add test for 'svnlook [cmd] -t'.
Add test for 'svnlook [cmd] -t'.

* subversion/tests/svnlook.py
  (verify_logfile): Helper function.
  (test_txn_flag): New test.
  (test_list): Run the new test, should pass.

git-svn-id: f8a4e5e023278da1e04e203c7fe051e3c4285d88@918211 13f79535-47bb-0310-9956-ffa450edef68

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