This does the most minimal set of changes to the host -- switching it from protocol 21 to 22 -- and produces a new set of observations with that change. Note that it's done in two steps, first by making an exact copy of the protocol 21 observations and then by updating them after the change with a re-observation. You can observe this change to see that the only things that changed are what you'd expect from the minimal change: some object hashes (and therefore footprints and such) of contracts.
The idea here is to merge this change, which is obviously semantically benign, before we land anything that makes a substantive change to the semantics of protocol 22, so that we have a better chance of isolating "what changed" in subsequent re-observations of the changed protocol 22.
This does the most minimal set of changes to the host -- switching it from protocol 21 to 22 -- and produces a new set of observations with that change. Note that it's done in two steps, first by making an exact copy of the protocol 21 observations and then by updating them after the change with a re-observation. You can observe this change to see that the only things that changed are what you'd expect from the minimal change: some object hashes (and therefore footprints and such) of contracts.
The idea here is to merge this change, which is obviously semantically benign, before we land anything that makes a substantive change to the semantics of protocol 22, so that we have a better chance of isolating "what changed" in subsequent re-observations of the changed protocol 22.