fix parsing schemeless connection URLs with PHP < 5.4.8

lib/Doctrine/DBAL/DriverManager.php

@@ -244,7 +244,15 @@ final class DriverManager
         // (pdo_)?sqlite3?:///... => (pdo_)?sqlite3?://localhost/... or else the URL will be invalid
         $url = preg_replace('#^((?:pdo_)?sqlite3?):///#', '$1://localhost/', $params['url']);
 
-        $url = parse_url($url);
+        // PHP < 5.4.8 doesn't parse schemeless urls properly.
+        // See: https://php.net/parse-url#refsect1-function.parse-url-changelog
+        if (PHP_VERSION_ID < 50408 && strpos($url, '//') === 0) {
+            $url = parse_url('fake:' . $url);
+
+            unset($url['scheme']);
+        } else {
+            $url = parse_url($url);
+        }
 
         if ($url === false) {
             throw new DBALException('Malformed parameter "url".');