made uid parameter optional in getPidIndex

src/posts.js

@@ -532,10 +532,20 @@ var async = require('async'),
 	}
 
 	Posts.getPidIndex = function(pid, uid, callback) {
-		callback = callback || function() {};
+		// Making uid optional
+		if ((!uid && !callback) || typeof uid === 'function') {
+			callback = uid;
+			uid = undefined;
+		}
+
 		async.parallel({
 			settings: function(next) {
-				user.getSettings(uid, next);
+				if (uid) {
+					user.getSettings(uid, next);
+				} else {
+					// No uid specified, so return empty object so that the check below will assume regular topic post sorting
+					next(null, {});
+				}
 			},
 			tid: function(next) {
 				Posts.getPostField(pid, 'tid', next);