Only use options as ajax context if incoming options context property is undefined; fixes #6727.

Author: dmethvin

src/ajax.js

@@ -202,7 +202,7 @@ jQuery.extend({
 		var s = jQuery.extend(true, {}, jQuery.ajaxSettings, origSettings),
 			jsonp, status, data, type = s.type.toUpperCase();
 
-		s.context = origSettings && origSettings.context || s;
+		s.context = origSettings.context !== undefined? origSettings.context : s;
 
 		// convert data if not already a string
 		if ( s.data && s.processData && typeof s.data !== "string" ) {