Out of band change notification shows `untitled.ipynb` for new files after renaming

[3coins]

Steps to reproduce

1. Create a new notebook file, rename to hello-world.ipynb
2. Open the file in JSON editor (Open With -> Editor)
3. Make a change to the file in editor
4. A notification pops up about the change, but refers to untitled.ipynb.
5. The problem goes away after you close and re-open the notebook file.
6. Another issue with this flow is that the dirty flag is not rest on the notebook.