Notice: Undefined property: stdClass::$shadow in forum_node_update() (line 373 of /.../modules/forum/forum.module)

Problem/Motivation

Steps to reproduce

1. On a fresh standard install of Drupal, enable the forum module.
2. Post a forum topic at node/add/forum.
3. Go to admin/content and unpublish the node.

Result

You will receive an error:

Notice: Undefined property: stdClass::$shadow in forum_node_update() (line 373 of /.../modules/forum/forum.module)

The property is being checked with if ($node->shadow), but it may not be set at all.

Proposed resolution

Use if (!empty($node->shadow)) instead of if ($node->shadow). Patch in #1 implements this change.

Remaining tasks

None.

User interface changes

None.

API changes

None.

Original report by @kerala

" Notice: Undefined property: stdClass::$shadow in forum_node_update() (line 373 of C:\wamp\www\D-7.7\modules\forum\forum.module) "

I downloaded drupal 7.7 and installed a fresh copy on my localhost and I posted a forum topic.When i unpuplished the post going to home » Administration » content i got the above error message.(I did'nt install any contributed modules)
I am getting this error whenever i try to "publish or unpublish" a forum post from home » Administration » content section..
i got the same error message for my drupal 7.2 and 7.4 sites also..
Any idea?