On the log-addressing branch:  More fixes to svn_fs__compatible_version.
The version comparison was broken and version->tag was not well-defined.

* subversion/include/private/svn_fs_util.h
  (svn_fs__append_to_merged_froms): update docstring

* subversion/libsvn_fs_util/fs-util.c
  (add_compatility): fix version comparison
  (svn_fs__compatible_version): give tag member a defined value

Found by: danielsh

git-svn-id: https://svn.apache.org/repos/asf/subversion/branches/log-addressing@1511364 13f79535-47bb-0310-9956-ffa450edef68