Every write to packed revprops would wrongly add another newline
(empty entry) at the end of the respective manifest file.  This is
a scalability issue and does not affect correctness.

* subversion/libsvn_fs_fs/fs_fs.c
  (get_revprop_packname): don't add an empty path name after the last entry

git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1513874 13f79535-47bb-0310-9956-ffa450edef68