--- a/python/mozbuild/mozbuild/configure/__init__.py
+++ b/python/mozbuild/mozbuild/configure/__init__.py
@@ -356,7 +356,7 @@ def run(self, path=None):
- # All options should have been removed (handled) by now.
- for arg in self._helper:
- without_value = arg.split('=', 1)[0]
-- raise InvalidOptionError('Unknown option: %s' % without_value)
-+ print('Ignoring', without_value, ': Unknown option')
+ if self._help:
+ self._logger.warning(msg)
+ else:
+- raise InvalidOptionError(msg)
++ print(msg)
# Run the execution queue
for func, args in self._execution_queue: