When filtering self-referential mergeinfo don't discard empty mergeinfo.
When filtering self-referential mergeinfo don't discard empty mergeinfo.

See http://subversion.tigris.org/servlets/ReadMsg?list=dev&msgNo=137120

* subversion/libsvn_client/merge.c
  (filter_self_referential_mergeinfo): Don't filter empty svn:mergeinfo.

Suggested by: kameshj

### THIS WAS REVERTED IN r30509 ###

git-svn-id: f8a4e5e023278da1e04e203c7fe051e3c4285d88@870577 13f79535-47bb-0310-9956-ffa450edef68

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