Print a more user-oriented error message when the target to 'svn switch' is
not (or does not appear to be) in the same repository. Fixes issue #2337,
'Usability: misleading message when switching to a foreign repository'.

* subversion/svn/switch-cmd.c
  (svn_cl__switch): Wrap two error codes with a high-level error message.

git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1429996 13f79535-47bb-0310-9956-ffa450edef68