[MERGE] Fix bzr failing to stack when a server requests it and the branch it is pushing from cannot stack but the branch it should stack on can.

[Robert Collins]

Robert Collins has voted approve.
Status is now: Approved
Comment:
If we have
/repo/standalone/newbranch
repo has a shared repo
standalone has a non-shared repo
newbranch must make a new repo of its own, it can't use the one from 
/repo.

I have a NEWS entry, was there something more you wanted in NEWS?

For details, see: 
http://bundlebuggy.aaronbentley.com/project/bzr/request/%3C1237435799.15722.199.camel%40lifeless-64%3E
Project: Bazaar