Following up on r1437203, make sure we don't copy svn:mergeinfo from
foreign repositories.

* subversion/libsvn_client/copy.c
  (repos_to_wc_copy_single): Drop svn:mergeinfo for foreign copies.

* subversion/libsvn_client/copy_foreign.c
  (dir_change_prop,
   file_change_prop,
   svn_client__copy_foreign): Drop svn:mergeinfo.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1437587 13f79535-47bb-0310-9956-ffa450edef68