On the fsfs-format7 branch: fix handling of rep shared directories.

* subversion/libsvn_fs_fs/transaction.c
  (write_final_rev): make sure we don't overwrite the rev of a shared rep

git-svn-id: https://svn.apache.org/repos/asf/subversion/branches/fsfs-format7@1438423 13f79535-47bb-0310-9956-ffa450edef68