the postauth privsep child never had its compression buffers initialised.
the old buffer code would would because they were (fortunately) bzeroed,
but the new code is more paranoid.
There is probably a more minimal way to do this that I'm missing :)
a per connection state struct, add a initial API that could
be used for a proxy (see ssh-proxy.c)
Joint work with Matthias Pitzl, Stefan Rinkes, Bernhard Zaun and
Arne Becker.