What to do if VC-ROOT changes after checkout?

[Jari Aalto]

Suppose this:

        Person (b):
        $ checkout VC-ROOT
        $ ... update, commit, fo work

Now suppose that the original location VC-ROOT no longer exists. The
maintainer(a) had decided that the directory location is now elsewhere.

Person(b) has uncommitted changes, but is unable to ci, because (a)
has changed the directory location.

If there were:

        bzr admin --checkout --new-url <new location>
            =====
            For other admin type command now and in the future.

This would just do the right thing and person b could continue as usual
after the pointer to checkout location had been updated.

But now, what can be done to achieve same effect? What file in .bzr/
shoudl be changed?

Jari