Code review comment for lp://staging/~jelmer/bzr/hpss-get-inventories

> Up to you to wait for spiv's review.
Thanks.

I haven't heard from spiv in the last week, and I'd really like to get this landed so it gets some decent testing for 2.5.0. My recent changes should have addressed his concerns regarding the use of record streams, and I'm happy to tweak whatever is necessary later based on post-commit reviews.