[bkalman]

Keep in mind (if this wasn't clear) that the chunks are only probabilistically 4K: https://github.com/attic-labs/noms/blob/master/go/types/roll.... I.e. the thing that's "fixed" here is the chunk size we're aiming for. The chunks themselves could be of any size.

In any case, that's a good question - we might want to do something about that down the line. But, if we did change that constant, the structure of the trees will change, and all[1] the hashes will change.

[1] a small number will stay the same