Code review comment for lp:~mwhudson/loggerhead/sorry-rob

Hi gentle reviewer,

This branch, which depends on the iter_changes-forevar branch, contorts
slightly to avoid loading inventories on the +filediff page fragments,
which and then contorts some more so that all the inventory information
needed to render a revision page comparing against its parent is stored
in the filechange cache. On a wide tree like launchpad this means
revision and +filediff pages load about 10x faster once the cache is
populated.

Cheers,
mwh