Python 3 compatibility: Update calls to exec().
Python 3 compatibility:
Update calls to exec().

* subversion/tests/cmdline/svntest/main.py: Update calls to exec().


git-svn-id: f8a4e5e023278da1e04e203c7fe051e3c4285d88@877072 13f79535-47bb-0310-9956-ffa450edef68

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