Sharing repository across branches (was: What do I call a working tree that stores its revisions in a shared repository?)

[Stefan Monnier]

> So it seems to me that the far more common physical object probably
> ought to be a working tree using a shared repository, both for
> performance and disk usage reasons - but there's no simple name for

That reminds me:
1 - I couldn't find any info about the impact of sharing a repository
    between unrelated branches.  It is recommended to share repositories
    between branches, but it's not clear how to define "related
    branches", and it's even less clear what happens if I create
    a single repository in my $HOME and use it for every branch.

2 - Say I have a branch with its own repository and I want to create
    another branch and share the repository.  How can I do that?
    Is there a way to move a branch's repository up the tree (or move
    the branch down without moving the repository), or do I have to
    do it the expensive way (which recreates a completely new
    repository from the existing one)?

3 - Assuming number 2 can be solved satisfactorily, wouldn't make sense
    for "bzr clone" to suggest "move repository to closest common
    parent?" when needed so as to share the repository.


-- Stefan