message: build bft block with variant
diff: @@ -11,7 +11,7 @@ use crate::stake;
  use crate::transaction::{AuthenticatedTransaction, NoExtra};
  use chain_addr::Address;
  use chain_crypto::{
  - Curve25519_2HashDH, Ed25519Extended, SecretKey, SumEd25519_12, VerifiableRandomFunction,
  + Curve25519_2HashDH, Ed25519, SecretKey, SumEd25519_12, VerifiableRandomFunction,
  };
  pub struct BlockBuilder {
  @@ -121,7 +121,7 @@ impl BlockBuilder {
  }
  /// create a BFT Block. this block will be signed with the given private key
  - pub fn make_bft_block(mut self, bft_signing_key: &SecretKey<Ed25519Extended>) -> Block {
  + pub fn make_bft_block(mut self, bft_signing_key: &SecretKey<Ed25519>) -> Block {
  assert_ne!(self.common.chain_length, ChainLength(0));
  self.finalize_common(BlockVersion::Ed25519Signed);
  let bft_proof = BftProof {
  