bodge: Allow both str and repr to be used for configuration file name

This is because Python 2's and Python 3's configparser treat the two
differently and we're reusing that message.

tests/unit/test_configuration.py

@@ -80,7 +80,10 @@ def test_environment_config_errors_if_malformed(self):
 
         assert "section header" in str(err.value)  # error kind
         assert "1" in str(err.value)  # line number
-        assert repr(config_file) in str(err.value)  # file name
+        assert (  # file name
+            config_file in str(err.value) or
+            repr(config_file) in str(err.value)
+        )
 
 
 class TestConfigurationPrecedence(ConfigurationMixin):