Merge branch 't7578' of https://github.com/jitter/jquery into jitter-t7578

src/ajax.js

@@ -261,7 +261,7 @@ jQuery.extend({
 			};
 		}
 
-		if ( s.dataType === "script" && s.cache === null ) {
+		if ( s.dataType === "script" && s.cache === undefined ) {
 			s.cache = false;
 		}
 

test/unit/ajax.js

@@ -710,10 +710,10 @@ test("jQuery.getScript(String, Function) - no callback", function() {
 });
 
 test("jQuery.ajax() - JSONP, Local", function() {
-	expect(8);
+	expect(9);
 
 	var count = 0;
-	function plus(){ if ( ++count == 8 ) start(); }
+	function plus(){ if ( ++count == 9 ) start(); }
 
 	stop();
 
@@ -828,6 +828,17 @@ test("jQuery.ajax() - JSONP, Local", function() {
 			plus();
 		}
 	});
+
+	//#7578
+	jQuery.ajax({
+		url: "data/jsonp.php",
+		dataType: "jsonp",
+		beforeSend: function(){
+			strictEqual( this.cache, false, "cache must be false on JSON request" );
+			plus();
+			return false;
+		}
+	});
 });
 
 test("JSONP - Custom JSONP Callback", function() {