Handle issue with two concurrent JSONP requests that use the same callback name.

src/ajax.js

@@ -239,10 +239,6 @@ jQuery.extend({
 			var customJsonp = window[ jsonp ];
 
 			window[ jsonp ] = function( tmp ) {
-				data = tmp;
-				jQuery.handleSuccess( s, xhr, status, data );
-				jQuery.handleComplete( s, xhr, status, data );
-				
 				if ( jQuery.isFunction( customJsonp ) ) {
 					customJsonp( tmp );
 
@@ -258,6 +254,10 @@ jQuery.extend({
 				if ( head ) {
 					head.removeChild( script );
 				}
+				
+				data = tmp;
+				jQuery.ajax.handleSuccess( s, xhr, status, data );
+				jQuery.ajax.handleComplete( s, xhr, status, data );
 			};
 		}