I worked on this. In addition to -l, -L is also valid with -d.

> My guess is roundup-server forks then fails to open a log file

When roundup-server is run with a pid file it daemonizes. This changes
the directory to '/'. Any log file names that are not absolute (e.g.
logging.ini files used by the logging subsystem) will fail to open in /
and cause the server to exit.

I have failed so far to be able to make all these files absolute with os.path.abspath
or equivalent.