Unpublish don't work on IIS

I am using Publish Content on an IIS server, but don't know if this issue is related to that, but when I choose unpublish an error occurs. I have tracked down the problem to come from line 109 where the status is set to opposite: $node->status = !$node->status; I get a false instead of 0, and are therefore not able to save the node. If I change the line to $node->status = (int)!$node->status; I'm sure to get an integer and can save the node.