Add extra assert to ensure withdrawal creds are different

tests/core/pyspec/eth2spec/test/electra/sanity/blocks/test_deposit_transition.py

@@ -278,6 +278,9 @@ def test_deposit_transition__deposit_with_same_pubkey_different_withdrawal_crede
     indices_with_same_pubkey = [1, 3]
     for index in indices_with_same_pubkey:
         block.body.execution_requests.deposits[index].pubkey = block.body.deposits[0].data.pubkey
+        # ensure top-up deposit request withdrawal credentials are different than the deposit
+        assert (block.body.execution_requests.deposits[index].withdrawal_credentials
+                != block.body.deposits[0].data.withdrawal_credentials)
 
     block.body.execution_payload.block_hash = compute_el_block_hash_for_block(spec, block)
 
@@ -288,5 +291,6 @@ def test_deposit_transition__deposit_with_same_pubkey_different_withdrawal_crede
     assert len(state.pending_deposits) == deposit_request_count + deposit_count
     for index in indices_with_same_pubkey:
         assert state.pending_deposits[deposit_count + index].pubkey == deposit_requests[index].pubkey
+        # ensure withdrawal credentials are retained, rather than being made the same
         assert (state.pending_deposits[deposit_count + index].withdrawal_credentials
                 == deposit_requests[index].withdrawal_credentials)