Stable Loggerhead Branch

[Robert Collins]

I see it thusly:

We have a tarball of quality X in Debian and Ubuntu today.

If, at any point in time we think we have a revision of loggerhead of
quality Y > X, then we should make a tarball of it and get it shipped.

"stability", like 'finished' is a bit ephemeral - you might be
perfectly stable, and then a python change breaks everything. Or a
bzrlib change.

Ship improvements.

-Rob