A minor fix to transaction auto-balancing
A minor fix to transaction auto-balancing

It allows transactions like the following to auto-balance:

  1999/08/16 Sell AAPL
      Assets:Broker                    $585
      Expense:Broker:Commissions        $15
      Assets:Broker                -10 AAPL {$30} @ $60
      Income:Capital Gains

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