Opening document in VE with pending changes that are not visible for VE

Steps to reproduce:

1. Open a document in content mode
2. Make a change (to a field not supported in the visual editor) and NOT save it
3. Switch to the channel manager and open the same document in the visual editor

You should either not be able to open the document in VE or the pending changes should be discarded / saved to unpublished when moving away from the content perspective.