Actually I may have an idea. Change:

[handler_basic]
class=StreamHandler
args=(sys.stderr,)
formatter=plain

to

[handler_basic]
class=logging.handlers.RotatingFileHandler
args=('demo.log', 'a', 512000, 2)
formatter=plain

I'll bet running as a service requires that nothing to to 
stdout/stderr.

Also you probably want to drop:

[logger_roundup]
#DEBUG, INFO, WARNING, ERROR, CRITICAL
#also for root only NOTSET (all)
level=DEBUG
handlers=basic
qualname=roundup
propagate=0

to

[logger_roundup]
#DEBUG, INFO, WARNING, ERROR, CRITICAL
#also for root only NOTSET (all)
level=WARNING
handlers=basic
qualname=roundup
propagate=0

for production otherwise demo.log will be quite chatty.