get_beanstalk_revision.php

<?php

/**
 * This function looks for the directory that "wp-config.php" resides in
 * and then looks for a file named ".revision", the content of which is a
 * single integer set by Beanstalk upon deployment.
 *
 * The purpose is to version static resources so that browsers will
 * re-download any cached, outdated versions with the newer version.
 *
 * This will only work in environments that Beanstak deploys to.
 */
function get_beanstalk_revision() {

	if (file_exists(dirname(ABSPATH) . '/wp-config.php')) {
		$filename = dirname(ABSPATH) . '/.revision';
	} else {
		$filename = ABSPATH . '/.revision';
	}

	if (file_exists($filename)) {
		$output = file_get_contents($filename);
	} else {
		return false;
	}

	return $output;
}