fix wrong gc sequence

ext/session/session.c

@@ -543,9 +543,6 @@ static void php_session_initialize(void) /* {{{ */
 	php_session_reset_id();
 	PS(session_status) = php_session_active;
 
-	/* GC must be done before read */
-	php_session_gc();
-
 	/* Read data */
 	php_session_track_init();
 	if (PS(mod)->s_read(&PS(mod_data), PS(id), &val, PS(gc_maxlifetime)) == FAILURE) {
@@ -555,6 +552,10 @@ static void php_session_initialize(void) /* {{{ */
 		php_error_docref(NULL, E_NOTICE, "Failed to read session data: %s (path: %s)", PS(mod)->s_name, PS(save_path));
 		*/
 	}
+
+	/* GC must be done after read */
+	php_session_gc();
+
 	if (PS(session_vars)) {
 		zend_string_release(PS(session_vars));
 		PS(session_vars) = NULL;