Remove some rep-cache validation code that was not used. Change an
error to that expected by the caller, this will cause commits that
would previously have succeeded, and thus hidden the potential
future corruption, to fail.

* subversion/libsvn_fs_fs/rep-cache.c
  (rep_has_been_born): Remove.
  (svn_fs_fs__get_rep_reference): Return SVN_ERR_FS_CORRUPT as expected
   by caller.
  (svn_fs_fs__set_rep_reference): Remove parameter that is always false.

* subversion/libsvn_fs_fs/rep-cache.h
  (svn_fs_fs__get_rep_reference): Document error.
  (svn_fs_fs__set_rep_reference): Remove parameter, document error.

* subversion/libsvn_fs_fs/transaction.c
  (write_reps_to_cache): Adjust call.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1560673 13f79535-47bb-0310-9956-ffa450edef68