Fix error message encoding

- Use the correct unicode string for an error message, otherwise an
exception will generate another exception about incorrect type,
masking the original error.

Signed-off-by: Simo Sorce <simo@redhat.com>
Reviewed-By: Alexander Bokovoy <abokovoy@redhat.com>

ipalib/rpc.py

@@ -603,7 +603,8 @@ class KerbTransport(SSLTransport):
                     except (TypeError, UnicodeError):
                         pass
             if not token:
-                raise KerberosError(message="No valid Negotiate header in server response")
+                raise KerberosError(
+                    message=u"No valid Negotiate header in server response")
             token = self._sec_context.step(token=token)
             if self._sec_context.complete:
                 self._sec_context = None