Trust Zone titles reset after clicking "Update Model"

[craslaw]

Steps to reproduce:

1. Edit a Trust Zone title with F2 or Enter. If not already present, this causes an orange Update Model button to appear in the top right corner.
2. Click Update Model.

Any renamed Trust Zones are reset to their default name, in my case, "Intranet Office networks".

[craslaw]

This also impacts any properties added to a trust zone. They are all wiped after updating the model.