"they tried to consolidate 10 50k coins into one 500k coin, and ended up with 50k in change"
https://github.com/bitcoin/bitcoin/blob/d3d753578c1043ce3755f097ce96cc2388a08738/src/test/wallet_tests.cpp#L208This is the 50K change? Is it real? Is it spendable? Or is it a bug?
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EDIT: Some more:
"That was MtGox trying to consolidate 10 50k coins into a single large 500k coin. The extra 50k was added by some code in the official client that is a little too careful to avoid sub-cent change."
https://bitcoin.stackexchange.com/questions/3287/what-is-the-largest-transaction-by-value-to-date-for-bitcoin-currencyI'm still not sure exactly what that means, though.
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EDIT 1.5:
I think what it means is that they had a wallet with at least eleven 50K coins in it (maybe some other coins, maybe not), and they tried to pay themselves 500K BTC. Instead of using ten 50K coins and converting it into one 500K coin, it took eleven 50K coins and converted it into one 500K coin and one 50K coin.
In other words, the transaction is valid, and the change is valid. The bug was that the software used more coins than was necessary.
See
https://gitorious.org/bitcoin/luke-jr-bitcoin/commit/e7199041ed68440d85bafd24155b3f9b98b7b94d---
EDIT 2:
I bet they lost the private key on that 50K (BTC) coin - either permanently or it's sitting around somewhere waiting to be found.
Thanks for the very interesting link!
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EDIT 3:
Very interesting implications if they claim to a bankruptcy court that they lost that 50K BTC coin. It'd be plausible (especially given that the coin in question was caused by a bug and nothing from that address has ever been spent), but unprovable. And what can you do if 2, 5, 10 years later suddenly the coin gets spent? Nothing, really.
I guess it'd be the same thing with cash, but it's significantly harder to embezzle $30,000,000 in hundred dollar bills. Even hiding cash is somewhat harder.