[Nbd] 2.9.21 released

[Wouter V. <w...@ut...>]

Hi,

I just release 2.9.21. This release fixes a number of crashing bugs, and
upgrading is generally recommended.

The delay is due to the fact that I had originally hoped to be able to
incorporate some more patches, but those turned out not to be of the
quality that I'd hoped for; and these really can't wait anymore. Hence.

Regards,

-- 
The volume of a pizza of thickness a and radius z can be described by
the following formula:

pi zz a