Anyway, something to be aware of -- anywhere we have true, false or nil used in a hash calculation, now has a different hash in Spur vs. Cog. Maybe we should think about separating those objects' logical "value" hash from their identityHash in trunk..? That could be useful when we move to 64-bit someday..
Remember that Spur has a common header format for both 32-bit and 64-bit versions, so in both there is a 22-bit identityHash and hence the identityHashes of all objects in a 64-bit Spur image bootstrapped from a 32-bit Spur image will be _unchanged_. Convenient. So no need to worry. And it should be the case that a freshly bootstrapped 64-bit Spur image does not need to be rehashed to function properly.
Suprising that their identityHash needs to change for Spur but not to go to 64-bit.. Wait, I thought one of the benefits of 64-bit was to finally increase that small identityHash?