wallet: Use existing feerate instead of getting a new one

Courtesy of 1a6a0b0 from bitcoin#21083

Author: kwvg

src/wallet/spend.cpp

@@ -651,6 +651,11 @@ bool CWallet::CreateTransactionInternal(
         error = strprintf(_("Fee rate (%s) is lower than the minimum fee rate setting (%s)"), coin_control.m_feerate->ToString(FeeEstimateMode::DUFF_B), coin_selection_params.m_effective_feerate.ToString(FeeEstimateMode::DUFF_B));
         return false;
     }
+    if (feeCalc.reason == FeeReason::FALLBACK && !m_allow_fallback_fee) {
+        // eventually allow a fallback fee
+        error = _("Fee estimation failed. Fallbackfee is disabled. Wait a few blocks or enable -fallbackfee.");
+        return false;
+    }
 
     int nBytes{0};
     {
@@ -802,7 +807,7 @@ bool CWallet::CreateTransactionInternal(
                         txin.scriptSig = CScript();
                     }
 
-                    nFee = GetMinimumFee(*this, nBytes, coin_control, &feeCalc);
+                    nFee = coin_selection_params.m_effective_feerate.GetFee(nBytes);
 
                     return true;
                 };
@@ -911,12 +916,6 @@ bool CWallet::CreateTransactionInternal(
                     }
                 }
 
-                if (feeCalc.reason == FeeReason::FALLBACK && !m_allow_fallback_fee) {
-                    // eventually allow a fallback fee
-                    error = _("Fee estimation failed. Fallbackfee is disabled. Wait a few blocks or enable -fallbackfee.");
-                    return false;
-                }
-
                 if (nAmountLeft == nFeeRet) {
                     // We either added the change amount to nFeeRet because the change amount was considered
                     // to be dust or the input exactly matches output + fee.