When one single dependency of an unconfirmed transaction is already verified, this does not mean the parent is confirmed. We can skip checking its own dependencies though.
Information about the best known chain is added to wallet.dat. If this
information does not match the data in blkindex.dat, a rescan is automatically
performed, starting from the the last known block. When upgrading from a wallet
which does not have this information, no rescan is done automatically.
Change some internal data structures to keep track of spentness of each wallet transaction output separately, to support partially-spent transactions:
* an update to the data structures (vfSpent in CWalletTx instead of fSpent)
* a backward-compatible update to the wallet disk format. Old clients reading back an updated wallet will ignore partially spent transactions when creating new ones, and may report a wrong balance, though.
* some helper functions (CWalletTx: IsSpent, MarkSpent, MarkDirty to reset cached values, GetAvailableCredit which only counts unredeemed outputs)
Pieter Wuille