static const char *external_diff(void)
{
	static const char *external_diff_cmd = NULL;
	static int done_preparing = 0;

	if (done_preparing)
		return external_diff_cmd;
	external_diff_cmd = getenv("GIT_EXTERNAL_DIFF");
	if (!external_diff_cmd)
		external_diff_cmd = external_diff_cmd_cfg;
	done_preparing = 1;
	return external_diff_cmd;
}
Unknown