You've never done software development, have you?
I cannot think of the hundreds, nay, thousands of hours IPS must have put into 4.5 - all the testing, planning, trying to make things as smooth as possible for their customers to upgrade their sites, etc.
If the connection between the host and client is terminated, there's usually no way to tell the host process "hang on, something's wrong" and stop whatever processes are running, and record a stopping point (can you imagine if it was inside a query - I suppose a rollback is possible, but again, a lot of overhead for something that isn't likely going to occur).
The absolute safest way is to run the upgrade via a RDP or similar process, so that way if the client connection is cut, the VM running the upgrade can continue uninterrupted (because presumably the host machine is on a solid connection with redundancies for power, etc.).
This was unfortunately a case of bad luck on @Paul E. part, but I take exception blaming or insinuating that IPS is somehow "not determined enough".