version: do not hardcode master branch

include/version.php

@@ -5,18 +5,37 @@
 		date_default_timezone_set('UTC');
 		$root_dir = dirname(dirname(__FILE__));
 
-		if (is_dir("$root_dir/.git") && file_exists("$root_dir/.git/refs/heads/master")) {
+		if (is_dir("$root_dir/.git") && file_exists("$root_dir/.git/HEAD")) {
+			$head = trim(file_get_contents("$root_dir/.git/HEAD"));
 
-			$suffix = substr(trim(file_get_contents("$root_dir/.git/refs/heads/master")), 0, 7);
-			$timestamp = filemtime("$root_dir/.git/refs/heads/master");
+			if ($head) {
+				$matches = array();
 
-			define("GIT_VERSION_HEAD", $suffix);
-			define("GIT_VERSION_TIMESTAMP", $timestamp);
+				if (preg_match("/^ref: (.*)/", $head, $matches)) {
+					$ref = $matches[1];
 
-			return VERSION_STATIC . " ($suffix)";
-		} else {
-			return VERSION_STATIC;
+					$suffix = substr(trim(file_get_contents("$root_dir/.git/$ref")), 0, 7);
+					$timestamp = filemtime("$root_dir/.git/$ref");
+
+					define("GIT_VERSION_HEAD", $suffix);
+					define("GIT_VERSION_TIMESTAMP", $timestamp);
+
+					return VERSION_STATIC . " ($suffix)";
+
+				} else {
+					$suffix = trim($head, 0, 7);
+					$timestamp = filemtime("$root_dir/.git/HEAD");
+
+					define("GIT_VERSION_HEAD", $suffix);
+					define("GIT_VERSION_TIMESTAMP", $timestamp);
+
+					return VERSION_STATIC . " ($suffix)";
+				}
+			}
 		}
+
+		return VERSION_STATIC;
+
 	}
 
 	define('VERSION', get_version());