Push a failing assertion when calling start() while already running. …

…Resets anyway to keep other tests going. Fixes #314

qunit/qunit.js

@@ -369,6 +369,8 @@ QUnit = {
 		// ignore if start is called more often then stop
 		if ( config.semaphore < 0 ) {
 			config.semaphore = 0;
+			QUnit.pushFailure( "Called start() while already started (QUnit.config.semaphore was 0 already)" );
+			return;
 		}
 		// A slight delay, to avoid any current callbacks
 		if ( defined.setTimeout ) {
@@ -1048,6 +1050,8 @@ QUnit.load = function() {
 	}
 
 	if ( config.autostart ) {
+		// usually start() throws an error when called while already running (semaphore === 0)
+		QUnit.config.semaphore = 1;
 		QUnit.start();
 	}
 };