bug warning - importing QIFs into accts w/ mixed currencies

[cognitive.libertarian+ml at gmail.com]

* Derek Atkins <warlord at MIT.EDU> [2010-10-05 20:48]:
> 
> Um, what do you mean by "an account with existing transactions in
> multiple currencies"?  There is no existing GnuCash account that can
> hold transactions of multiple currencies, so I'm not sure what
> you're talking about or how to reproduce.

The account was created in one currency.  Then it accumulated
transactions with other accounts in the same currency, as well as some
transactions that crossed currencies (because the other side of the
transaction was an account holding another currency).  

Then a QIF file was imported, containing older transactions, and some
overlap with existing transactions.  Some of the overlapping
transactions matched existing transactions that crossed currencies.
It looks like the duplicates were not detected as duplicates.  But
somehow this caused the existing transactions to lose their exchange
rate, causing bogus figures in the accounts that weren't being merged.
I recall being asked which single currency to use for all the imported
transactions.  This suggests that the import tool has a currency
limitation.  And that's fair enough, and I can understand if the new
inbound transactions might be screwed up, but it shouldn't be changing
pre-existing transactions.  Both the new transaction and the existing
transaction that it duplicates were messed up.