Makes sure that status -1 (used when an internal error occured) will not tag...

Makes sure that status -1 (used when an internal error occured) will not tag jqXHR.readyState as complete (4).

src/ajax.js

@@ -503,7 +503,7 @@ jQuery.extend({
 			responseHeadersString = headers || "";
 
 			// Set readyState
-			jqXHR.readyState = status ? 4 : 0;
+			jqXHR.readyState = status > 0 ? 4 : 0;
 
 			var isSuccess,
 				success,