[MERGE][#294479] Fix many round-trips when pushing to pre-1.13 HPSS pack repository

[Martin Pool]

Martin Pool has voted approve.
Status is now: Approved
Comment:
That seems reasonable to me.

For details, see: 
http://bundlebuggy.aaronbentley.com/project/bzr/request/%3C20090324025845.GA24980%40steerpike.home.puzzling.org%3E
Project: Bazaar