When a pass of CreateTransaction fails to select enough bitcoin to meet the nFeeNeeded the next pass through may select a far smaller collection of inputs.  Currently it will continue to use the old fee amount based on the larger set of inputs, which can cause a non-trivial over-payment.

This may be the cause of the behavior reported here: https://www.reddit.com/r/Bitcoin/comments/5ltw5n/bitcoin_core_v0131_sends_enormously_high_fee/

Long ago fixing this was tricky due to a catch-22 between signing the transaction and knowing how much fee was required.  But after #9465 the whole algorithm will run using a dummy signature, so when there is already a change output fixing up the fee after finding a sufficient transaction should be a matter of a ~2 line change.

{
    AssertLockHeld(cs_wallet); 
    int64_t nRet = nOrderPosNext++;
    if (pwalletdb) {
        pwalletdb->WriteOrderPosNext(nOrderPosNext);
    } else {
        CWalletDB(strWalletFile).WriteOrderPosNext(nOrderPosNext);
    }
    return nRet;
}
bool CWallet::AccountMove(std::string strFrom, std::string strTo, CAmount nAmount, std::string strComment)