[MERGE][bug #300177] Pass compression_parent as part of 'get_record_stream'

[Robert Collins]

Robert Collins has voted comment.
Status is now: Semi-approved
Comment:
I'd be a lot happier with this if the compression_parent field was only 
on KnitContentFactory, which is the only content factory for which it 
makes sense.

For details, see: 
http://bundlebuggy.aaronbentley.com/project/bzr/request/%3C498CB306.30201%40arbash-meinel.com%3E
Project: Bazaar