Handling of Zcash consensus branch ID will cause problems for future upgrades that don't change tx version

[daira]

See 7707109#commitcomment-36629702 :

This will work for now, but it's not the ideal way to code this. In general you're assuming that the consensus branch ID is determined by the transaction version, which will cause a problem for any upgrade that doesn't change the tx version (as Blossom didn't). Furthermore there could be multiple tx versions valid at the same time, but the consensus branch ID changes at the upgrade regardless of which tx version is actually used.

[OttoAllmendinger]

thanks for the heads up!

[zquestz]

Just a note, this already happened on testnet.

// Fix the consensusBranchId to the latest valid value.
bitgo.networks.zcashTest.consensusBranchId['4'] = 0xf5b9230b

[dractw]

And happened once again with 0xe9ff75a6 :)