protected function sanitize_requires_php( $version ) {
		$version = trim( $version );

		// x.y or x.y.z
		if ( $version && ! preg_match( '!^\d+(\.\d+){1,2}$!', $version ) ) {
			$this->warnings['requires_php_header_ignored'] = true;
			// Ignore the readme value.
			$version = '';
		}

		return $version;
	}