core: fix london-check to avoid duplication (ethereum#23333)

Co-authored-by: lxex <[email protected]>

core/state_transition.go

@@ -287,6 +287,7 @@ func (st *StateTransition) TransitionDb() (*ExecutionResult, error) {
 	sender := vm.AccountRef(msg.From())
 	homestead := st.evm.ChainConfig().IsHomestead(st.evm.Context.BlockNumber)
 	istanbul := st.evm.ChainConfig().IsIstanbul(st.evm.Context.BlockNumber)
+	london := st.evm.ChainConfig().IsLondon(st.evm.Context.BlockNumber)
 	contractCreation := msg.To() == nil
 
 	// Check clauses 4-5, subtract intrinsic gas if everything is correct
@@ -319,15 +320,16 @@ func (st *StateTransition) TransitionDb() (*ExecutionResult, error) {
 		st.state.SetNonce(msg.From(), st.state.GetNonce(sender.Address())+1)
 		ret, st.gas, vmerr = st.evm.Call(sender, st.to(), st.data, st.gas, st.value)
 	}
-	if !st.evm.ChainConfig().IsLondon(st.evm.Context.BlockNumber) {
+
+	if !london {
 		// Before EIP-3529: refunds were capped to gasUsed / 2
 		st.refundGas(params.RefundQuotient)
 	} else {
 		// After EIP-3529: refunds are capped to gasUsed / 5
 		st.refundGas(params.RefundQuotientEIP3529)
 	}
 	effectiveTip := st.gasPrice
-	if st.evm.ChainConfig().IsLondon(st.evm.Context.BlockNumber) {
+	if london {
 		effectiveTip = cmath.BigMin(st.gasTipCap, new(big.Int).Sub(st.gasFeeCap, st.evm.Context.BaseFee))
 	}
 	st.state.AddBalance(st.evm.Context.Coinbase, new(big.Int).Mul(new(big.Int).SetUint64(st.gasUsed()), effectiveTip))