Also test untouched logger config.

Passing in ``None``, should result in no logger changes.

tests/test_logger.py

@@ -21,6 +21,8 @@ def test_get_logger_by_name():
 def test_configure():
     # we can configure the logger.
     my_logger = logging.getLogger("ulif.diceware")
+    configure(None)
+    assert my_logger.level == 0
     configure(0)
     assert my_logger.level == logging.INFO
     configure(2)