On the 'move-tracking-2' branch: Correct some error messages.

* subversion/svnmover/svnmover.c
  (execute): Pass 'mv' instead of 'cp' for error messages in the move
    command.

git-svn-id: https://svn.apache.org/repos/asf/subversion/branches/move-tracking-2@1639625 13f79535-47bb-0310-9956-ffa450edef68