Scenario: A contract deployed by another contract cannot be upgraded

[gfusee]

When the parent contract upgrades its child contract, the transaction doesn't fail but the child contract doesn't have its code changed

Here is a repo that reproduces the issue: https://github.com/gfusee/upgrade-contract-error-demo

This bug happens in both 1.5.19 and the 1.5.25 versions of the VM

[andrei-marinica]

The contract to be upgraded is missing an upgrade function, similar to init. This has become mandatory in VM 1.5. I'm almost sure that is the problem here.

Granted, the debugging experience is leaving much to be desired. We'll see what we can do.