Config object is always live - get_str() fails

When attempting to

    let cfg = repo.config().expect("Failed to obtain config struct");
    let name = cfg.get_str("user.name").unwrap(); // <<<  fails here
    let email = cfg.get_str("user.email").unwrap();

it always fails with:

thread 'main' panicked at 'called `Result::unwrap()` on an `Err` value: Error { code: -1, klass: 7, message: "get_string called on a live config object" }', src/libcore/result.rs:999:5
stack backtrace:

which I backtraced down to is_readonly returning 1.

int git_config_get_string(
	const char **out, const git_config *cfg, const char *name)
{
	git_config_entry *entry;
	int ret;

	if (!is_readonly(cfg)) { // <<<< always fails
		git_error_set(GIT_ERROR_CONFIG, "get_string called on a live config object");
		return -1;
	}

	ret = get_entry(&entry, cfg, name, true, GET_ALL_ERRORS);
	*out = !ret ? (entry->value ? entry->value : "") : NULL;

	git_config_entry_free(entry);

	return ret;
}

Minimal fully runnable demo of the issue: https://github.com/drahnr/gitconfigtest/

$ git config user.name
Bernhard

works fine

(Or maybe I do not understand the meaning of this error and it's a layer 8 problem)

Start by running the linked minimal demo and tracing repo.config(), get_str(), and the underlying git_config_get_string call, especially the is_readonly check. Compare the live config behavior with the read-only lookup path; done means user.name and user.email can be retrieved without the reported error.