Report duplicate tree conflict errors in just one place (follow-up to r38872).
Report duplicate tree conflict errors in just one place (follow-up
to r38872).

* subversion/libsvn_client/merge.c
  (tree_conflict_on_add): Remove redundant error handling.


git-svn-id: f8a4e5e023278da1e04e203c7fe051e3c4285d88@878970 13f79535-47bb-0310-9956-ffa450edef68

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