Follow-up to r25038, simplify errors returned by get_wc_or_repos_mergeinfo().
Follow-up to r25038, simplify errors returned by get_wc_or_repos_mergeinfo().

* subversion/libsvn_client/merge.c
  (get_wc_or_repos_mergeinfo): Just return SVN_ERR_ENTRY_MISSING_URL if a
  missing merge target (or any other cause) results in an abbreviated entry
  that has no URL.


git-svn-id: f8a4e5e023278da1e04e203c7fe051e3c4285d88@865266 13f79535-47bb-0310-9956-ffa450edef68

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