message: fix btc swap from external wallet
diff: @@ -740,11 +740,10 @@ class Exchange extends PureComponent<any, any> {
  : sellBalance.isGreaterThanOrEqualTo(buyFee)
  hasEnoughBalanceForFullPayment =
  - fromType === AddressType.Custom ||
  isTokenSell
  ? hasEnoughBalanceForAmount && ethBalance.isGreaterThanOrEqualTo(sellFee)
  - : isTokenBuy
  - ? hasEnoughBalanceForAmount && ethBalance.isGreaterThanOrEqualTo(buyFee)
  + : fromType === AddressType.Custom || isTokenBuy
  + ? hasEnoughBalanceForBuyFee && ethBalance.isGreaterThanOrEqualTo(buyFee)
  : sellBalance.isGreaterThanOrEqualTo(new BigNumber(amount).plus(sellFee))
  if (hasEnoughBalanceForFullPayment) {
  