Bug#705155: debbugs: "control:" commands sent to *-close addresses get ignored

Control: retitle -1 allow Control: commands at -done and -forwarded

On Wed, 04 Jan 2017, Ben Finney wrote:
> I hope that provides a use case, so that you *do* know why this is
> wanted.

I've become convinced that this is useful in the time since I documented
it. [Indeed, if it was trivial to implement, I would have added it right
then too.] I just haven't had a chance to do the legwork to implement it
properly.