When doing log with merge data, don't bother getting combined mergeinfo for revision 0, as it doesn't have any.
When doing log with merge data, don't bother getting combined mergeinfo for
revision 0, as it doesn't have any.

* subversion/libsvn_repos/log.c
  (get_combined_mergeinfo): If checking revision 0, just return an empty
  mergeinfo hash.

jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion