Proposed schedule for 6.4

[David Edmundson]

> Disclaimers: I always understood the repository and "soft feature"
> freeze to be an Alpha release

No, we want to make sure there's no super-duper big changes happening
around the same time
that someone is trying to make tarballs and packages. It gets messy,
things might not even compile or log in.

There's no point asking users to check the state of things if we
haven't checked it ourselves.
We definitely want to keep that soft freeze before a release of any name.

David