Always use GENESIS_FORK_VERSION to sign BLSToExecutionChange message

specs/capella/beacon-chain.md

@@ -472,7 +472,8 @@ def process_bls_to_execution_change(state: BeaconState,
     assert validator.withdrawal_credentials[:1] == BLS_WITHDRAWAL_PREFIX
     assert validator.withdrawal_credentials[1:] == hash(address_change.from_bls_pubkey)[1:]
 
-    domain = get_domain(state, DOMAIN_BLS_TO_EXECUTION_CHANGE)
+    # Fork-agnostic domain since address changes are valid across forks
+    domain = compute_domain(DOMAIN_BLS_TO_EXECUTION_CHANGE, genesis_validators_root=state.genesis_validators_root)
     signing_root = compute_signing_root(address_change, domain)
     assert bls.Verify(address_change.from_bls_pubkey, signing_root, signed_address_change.signature)
 

tests/core/pyspec/eth2spec/test/capella/block_processing/test_process_bls_to_execution_change.py

@@ -177,16 +177,21 @@ def test_invalid_bad_signature(spec, state):
 @with_capella_and_later
 @spec_state_test
 @always_bls
-def test_current_fork_version(spec, state):
-    """
-    It should be identical to the `test_success` test case.
-    It is just for comparing with `test_invalid_previous_fork_version`.
-    """
-    signed_address_change = get_signed_address_change(spec, state, fork_version=state.fork.current_version)
+def test_genesis_fork_version(spec, state):
+    signed_address_change = get_signed_address_change(spec, state, fork_version=spec.config.GENESIS_FORK_VERSION)
 
     yield from run_bls_to_execution_change_processing(spec, state, signed_address_change)
 
 
+@with_capella_and_later
+@spec_state_test
+@always_bls
+def test_invalid_current_fork_version(spec, state):
+    signed_address_change = get_signed_address_change(spec, state, fork_version=state.fork.current_version)
+
+    yield from run_bls_to_execution_change_processing(spec, state, signed_address_change, valid=False)
+
+
 @with_capella_and_later
 @spec_state_test
 @always_bls

tests/core/pyspec/eth2spec/test/helpers/bls_to_execution_changes.py

@@ -17,10 +17,10 @@ def get_signed_address_change(spec, state, validator_index=None, withdrawal_pubk
     if to_execution_address is None:
         to_execution_address = b'\x42' * 20
 
-    if fork_version is None:
-        domain = spec.get_domain(state, spec.DOMAIN_BLS_TO_EXECUTION_CHANGE)
-    else:
-        domain = spec.compute_domain(spec.DOMAIN_BLS_TO_EXECUTION_CHANGE, fork_version, state.genesis_validators_root)
+    domain = spec.compute_domain(
+        spec.DOMAIN_BLS_TO_EXECUTION_CHANGE,
+        fork_version=fork_version,
+        genesis_validators_root=state.genesis_validators_root)
 
     address_change = spec.BLSToExecutionChange(
         validator_index=validator_index,