This turns STRICTENC turn into a softforking-safe change (even though it is not intended as a consensus rule), and as a result guarantee that using it for mempool validation only results in consensus-valid transactions in the mempool.
This turns STRICTENC turn into a softforking-safe change (even though it is not intended as a consensus rule), and as a result guarantee that using it for mempool validation only results in consensus-valid transactions in the mempool.