weave branch --basis

[Wouter van Heyst]

I should really stop starting at code and go to sleep, but, annoyed at
the lack of --basis nowadays, I'm trying (badly) to resurrect it.

As a first shot, I've changed bzrlib/clone.py to do:

    branch_to = Branch.initialize(to_location)
    if basis_branch is not None:
        basis_branch.push_stores(branch_to)

Which looks a bit like the code originally in
aaron.bentley at utoronto.ca-20050925050117-dc4b46505adfc0d7 (as seen on
http://goffredo-baroncelli.homelinux.net/bazaar/bazaar-NG?cmd=revision;revid=aaron.bentley@utoronto.ca-20050925050117-dc4b46505adfc0d7
thanks to Goffredo)

And this has already sped up things, but this can hardly be right nor
complete, can it?

Wouter van Heyst