[D7] Deleting node type leaves orphan nodes

D7 backport of #232327: Deleting node type leaves orphan nodes

The steps required to reproduce the bug are:

1. Create node of content type X
2. Delete the content type X
3. Go to node/n/edit where n is the id of the node you created in step one.

What I expected to see was a drop-down list of current content types I could change my node to.

Instead I got this ugly error message:
warning: call_user_func_array() [function.call-user-func-array]: First argument is expected to be a valid callback, 'blog_node_form' was given in /home/.saul/lindenlion/michaelkillian.com/includes/form.inc on line 358.

I had to go to the mysql database and manually change the content type entry of my node to something that was available.