It is a part of the consensus layer. The btcd bug happened because they were checking a segwit v0 rule against all txs at the network layer when they shouldn't have been

benthecarman

> The problem was the bug was in the networking code not the consensus layer code.

Oh, didn't know that the taproot implementation is not part of the consensus layer.

Thanks for clarifying!

franzap

bitcoin

How do devs decide who should have commit access?

There is a massive test suite that has tests that cover btcd bug and btcd was using them. The problem was the bug was in the networking code not the consensus layer code. 

It is extremely hard to have an exact copy of the rules, you have to remember that if there is a bug in bitcoin core, that bug is a consensus rule. Competiting implementations is just really not a good idea. Ethereum has many implementations and one of they have consensus problems all the time. 