Update generic error parsing to include 4xx errors

Author: adev-code

botocore/parsers.py

@@ -300,7 +300,7 @@ def _is_generic_error_response(self, response):
         # non sensical parsed data.
         # To prevent this case from happening we first need to check
         # whether or not this response looks like the generic response.
-        if response['status_code'] >= 500:
+        if response['status_code'] >= 400:
             if 'body' not in response or response['body'] is None:
                 return True