[merge] refactor pack repositories

[Martin Pool]

Updated version attached.  I'm trying to have more commonality between
the different indexes so that I can add one without patching it into
every place -- ideally it would be something like

class RepositoryPackCollection

  def commit_write_group():
     ...
     for index_manager in  self._index_managers:
        index_manager.commit()

or something...
-------------- next part --------------
A non-text attachment was scrubbed...
Name: 20070921-pack-repo-cleanups-2.diff
Type: text/x-diff
Size: 49546 bytes
Desc: not available
Url : https://lists.ubuntu.com/archives/bazaar/attachments/20070921/1d7c8742/attachment-0001.bin