Don't call os.pid() the default kwargs to atexit_print_messages
Don't call os.pid() the default kwargs to atexit_print_messages

Whilst it has no side-effects, this results in non-reproducible output when
generating the certbot documentation:

    http://i.imgur.com/Q6VGi9S.jpg

Signed-off-by: Chris Lamb <711c73f64afdce07b7e38039a96d2224209e9a6c@chris-lamb.co.uk>

bsmr-misc-forks/letsencrypt,bsmr-misc-forks/letsencrypt,letsencrypt/letsencrypt,jsha/letsencrypt,lmcro/letsencrypt,stweil/letsencrypt,jsha/letsencrypt,jtl999/certbot,letsencrypt/letsencrypt,stweil/letsencrypt,lmcro/letsencrypt,jtl999/certbot