Redirect when editing a node that have a pending revision

The attached patch fixes an issue when trying to edit a node that have a pending revision. In that case this module forces the load of the latests pending revision instead with a node_load() call, but by doing that the 'created' field is dropped if you save this pending revision.

Here is what happen:
1. Create a new revision of a node => this revision is now pending
2. Try to edit the node
3. node_form() is called, which calls node_object_prepare()
4. node_object_prepare() set correctly '$node->date' field (which will become the new 'created' node field if we submit the form)
5. node_invoke_nodeapi($node, 'prepare') is called
6. revision_moderation_nodeapi('prepare') is called, then the node is overriden because of a call to node_load()... so the $node->date info is lost
7. During the form display, the 'date' field is empty, and so if we submit the form we drop the 'created' node info... data loss !

So what I suggest is to redirect to the correct pending revision edition form, instead of calling node_load().

The patch prevents too a useless redirection (and probably a dead loop) when we are already trying to edit the latest pending revision (before that patch, a useless node_load() call was made as we already have the good $node).