fix toPid link for post by guest

templates/partials/topic/post.tpl

@@ -29,9 +29,8 @@
 
 			<small data-editor="{posts.editor.userslug}" component="post/editor" class="hidden">[[global:last_edited_by, {posts.editor.username}]] <span class="timeago" title="{posts.relativeEditTime}"></span></small>
 
-
 			<!-- IF posts.toPid -->
-			<button component="post/parent" class="btn btn-xs btn-default hidden-xs" data-topid="{posts.toPid}"><i class="fa fa-reply"></i> @{posts.parent.username}</button>
+			<button component="post/parent" class="btn btn-xs btn-default hidden-xs" data-topid="{posts.toPid}"><i class="fa fa-reply"></i> @<!-- IF posts.parent.username -->{posts.parent.username}<!-- ELSE -->[[global:guest]]<!-- ENDIF posts.parent.username --></button>
 			<!-- ENDIF posts.toPid -->
 
 			<span>