ra_serf: fix test merge_fails_if_subtree_is_deleted_on_src, analog to r26339.
ra_serf: fix test merge_fails_if_subtree_is_deleted_on_src, analog to r26339.

* subversion/libsvn_ra_serf/mergeinfo.c
  (global): add include svn_path.h
  (svn_ra_serf__get_mergeinfo): to avoid getting mergeinfo on an item that 
   doesn't exist in HEAD, use the peg revision and the baseline-collection url 
   as target for the mergeinfo REPORT.


git-svn-id: f8a4e5e023278da1e04e203c7fe051e3c4285d88@866591 13f79535-47bb-0310-9956-ffa450edef68

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