Code review comment for lp:~stevenk/launchpad/link-branch-to-private-bug

Oh, and it will also violate an existing axiom:
 - public branches can never become private

And will be surprising for folk that have toggle a branch public explicitly to have it become private when *anyone* links it to a private bug.

I'm 'upgrading' my review to needs-fixing (and I think it needs design level fixing, not a small matter of code).