Fix issue #1313: Copying between two different repositories gave an incomprehensible error message.
Fix issue #1313: Copying between two different repositories gave an
incomprehensible error message.

* subversion/libsvn_client/copy.c
  (repos_to_repos_copy): Detect the condition and produce a better
    error message.

jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion