Method underscores_nested

tests/config.py:713–717

(self)

            assert c.foo_bar == "biz"

        def underscores_nested(self):
            os.environ["INVOKE_FOO_BAR"] = "biz"
            c = Config(defaults={"foo": {"bar": "notbiz"}})
            c.load_shell_env()
            assert c.foo.bar == "biz"

        def both_types_of_underscores_mixed(self):
            os.environ["INVOKE_FOO_BAR_BIZ"] = "baz"