Reraise original exception to debug test failure on travis

Signed-off-by: Michal Čihař <michal@cihar.com>

weblate/trans/machine/base.py

@@ -233,6 +233,7 @@ class MachineTranslation(object):
                 self.request_url,
                 self.request_params,
             )
+            raise
             raise MachineTranslationError('{}: {}'.format(
                 exc.__class__.__name__,
                 str(exc)