Fix part of issue 779.
Fix part of issue 779.

* subversion/libsvn_subr/io.c (svn_io_run_diff): Treat a return value
  of 2 from the diff process as an error. 


git-svn-id: f8a4e5e023278da1e04e203c7fe051e3c4285d88@843495 13f79535-47bb-0310-9956-ffa450edef68

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