On the log-message-templates branch, enforce the absolute-paths
requirement of svn_client_get_log_message_templates().

* subversion/libsvn_client/commit_util.c
  (svn_client_get_log_message_templates): Assert that the caller provided
   absolute paths, instead of making paths absolute. This is possible
   now that r1623974 has been merged from trunk.


git-svn-id: https://svn.apache.org/repos/asf/subversion/branches/log-message-templates@1623989 13f79535-47bb-0310-9956-ffa450edef68