Scratch that, just punting on Opera and 304s for now - there may not be a good...

Scratch that, just punting on Opera and 304s for now - there may not be a good solution here. Fixes #6060.

src/ajax.js

@@ -629,11 +629,8 @@ jQuery.extend( jQuery.ajax, {
 		try {
 			// IE error sometimes returns 1223 when it should be 204 so treat it as success, see #1450
 			return !xhr.status && location.protocol === "file:" ||
-				( xhr.status >= 200 && xhr.status < 300 ) ||
-				xhr.status === 304 || xhr.status === 1223 ||
-				// Opera returns a status of 0 for redirects -
-				// We can detect this by the fact that Opera also doesn't return any headers
-				xhr.status === 0 && !xhr.getAllResponseHeaders();
+				xhr.status >= 200 && xhr.status < 300 ||
+				xhr.status === 304 || xhr.status === 1223;
 		} catch(e) {}
 
 		return false;
@@ -652,8 +649,7 @@ jQuery.extend( jQuery.ajax, {
 			jQuery.ajax.etag[url] = etag;
 		}
 
-		// Opera returns 0 when status is 304
-		return xhr.status === 304 || xhr.status === 0 && !xhr.getAllResponseHeaders();
+		return xhr.status === 304;
 	},
 
 	httpData: function( xhr, type, s ) {