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

[Andrew Bennetts]

This fixes two issues:

 * in bzr.dev, there's a regression vs. 1.13 causing lots of little append round
   trips when pushing to a pack repo on pre-1.13 smart server.

 * as a side-effect, this fixes the specific case that has been bothering people
   for a long time: that pushing to a *stacked* pack repository via pre-1.13
   HPSS is slow.  That was <https://bugs.launchpad.net/bzr/+bug/294479>.

In both cases upgrading the server would fix the issue (and give much better
network performance in general), but within reason we don't want to make life
too painful for people just because their server is a bit old.

This patch is a little bit of a hack, but IMO it's not too outrageous.  Thanks
to Robert for some pointers about where best to place this hack.

-Andrew.

-------------- next part --------------
A non-text attachment was scrubbed...
Name: remote-pack-hack-4192.patch
Type: text/x-diff
Size: 12580 bytes
Desc: not available
Url : https://lists.ubuntu.com/archives/bazaar/attachments/20090324/2d8a1cd2/attachment.bin