Comment 12 for bug 1520377

I found the proper fix for this. The problem was that when closing the second-last terminal we grab some metadata to rebuild the tab properly. We were grabbing the tab title as metadata and then setting it so that it was acting as a custom tab title. You can see this by double clicking the "frozen" tab title to edit it, then deleting the contents. This reverts to paying attention to shell escape codes and changing as expected. All I needed to do was slightly alter the notebook get_child_metadata to account for the fact that a tab title may not be customised.

Fixed in gtk branch rev 1649