It would a major improvement in cleanness if 
roundup would support a Mailman style installation.

Mailman uses c wrappers for the mail and cgi commands.
They check the group permissions, calling parameters
and can use setgid bits. It makes security permission
bugs less likely.

All binaries and data get installed in the directory
of one user (usually ~mailman). There is a bin/paths.py
which sets the path for the modules ~mailman/Mailman.
The data for the lists also reside there
(~mailman/lists , ~mailman/data, ~mailman/log)
This allows for several versions to be installed and
everything related to one version is in one place for
the administrators.
So no more patching of python path and giving the
instances directory
in default cases. Just call ~roundup/bin/admin and only
give it the name of the tracker.

The latter shows how installing everything in one place
can help
to make the usage simple, because the default
directories are known.
I find that I type /home/roundup/instances/testroundup
way to often during installation. 

In short: Please check out the clear design of the mailman
and its regular installation at ~mailman. Just mimic it.