Allow P-chain to sign off on updates to L1 validator sets. This would prevent the following scenario. Suppose there is a chain of validator set updates:
V1 --> V2 --> V3
If the on-chain update to V2 is skipped (e.g., if the gas threshold is exceeded), but there is no longer a quorum of V1 validators online, then it would be impossible to gather enough signatures to register V3 on-chain. In this scenario, we add the option to have the P-chain validator set, which is the source of truth, to sign off on the V3 update.
Allow P-chain to sign off on updates to L1 validator sets. This would prevent the following scenario. Suppose there is a chain of validator set updates:
V1 --> V2 --> V3
If the on-chain update to V2 is skipped (e.g., if the gas threshold is exceeded), but there is no longer a quorum of V1 validators online, then it would be impossible to gather enough signatures to register V3 on-chain. In this scenario, we add the option to have the P-chain validator set, which is the source of truth, to sign off on the V3 update.