system/I18n/Time.php
protected static function hasRelativeKeywords(string $time): bool
	{
		// skip common format with a '-' in it
		if (preg_match('/[0-9]{4}-[0-9]{1,2}-[0-9]{1,2}/', $time) !== 1)
		{
			return preg_match(static::$relativePattern, $time) > 0;
		}

		return false;
	}
protected static function hasRelativeKeywords(string $time): bool
	{
		// skip common format with a '-' in it
		if (preg_match('/[0-9]{4}-[0-9]{1,2}-[0-9]{1,2}/', $time) !== 1)
		{
			return preg_match(static::$relativePattern, $time) > 0;
		}

		return false;
	}
Check a time string to see if it includes a relative date (like 'next Tuesday').

@param string $time

@return boolean