convert: use git diff-tree -Cn% instead of --find-copies=n% for older git The option --find-copies was added in a later git version than the one included in Debian squeeze-lts (1.7.2.5), probably around 1.7.4.

changelog: rely on transaction for finalization Instead of calling 'cl.finalize()' by hand (possibly at a bogus time) we register it in the transaction during 'delayupdate' and rely on 'tr.close()' to call it at the right time.

transaction: allow registering a finalization callback The new 'addfinalize' method allows people to register a callback to be triggered when the transaction is closed. This aims to get rid of explicit calls to 'changelog.finalize'. This also obsoletes the 'onclose' function but removing it is not in the scope of this series.

changelog: handle writepending in the transaction The 'delayupdate' method now takes a transaction object and registers its '_writepending' method for execution in 'transaction.writepending()'. The hook can then use 'transaction.writepending()' directly. At some point this will allow the addition of other file creation during writepending.