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.

transaction: add 'writepending' logic The contents of the transaction must be flushed to disk before running a hook. But it must be flushed to a special file so that the normal reader does not use it. This logic is currently in the changelog only. We add some facility to register such operations in the transaction itself.

changelog: rework the delayupdate mechanism The current way we use the 'delayupdate' mechanism is wrong. We call 'delayupdate' right after the transaction retrieval, then we call 'finalize' right before calling 'tr.close()'. The 'finalize' call will -always- result in a flush to disk, making the data available to all readers. But the 'tr.close()' may be a no-op if the transaction is nested. This would result in data: 1) exposed to reader too early, 2) rolled back by other part of the transaction after such exposure So we need to end up in a situation where we call 'finalize' a single time when the transaction actually closes. For this purpose we need to be able to call 'delayupdate' and '_writepending' multiple times and 'finalize' once. This was not possible with the previous state of the code. This changeset refactors the code to makes this possible. We buffer data in memory as much as possible and fall-back to writing to a ".a" file after the first call to '_writepending'.

merge with stable