requirements.txt contains pkg-resources==0.0.0
The line:
pkg-resources==0.0.0
breaks the installation of the dss cli tool. I assume it contains this line due to a bug in Ubuntu documented in [1] and [2].
[1] https://bugs.launchpad.net/ubuntu/+source/python-pip/+bug/1635463 [2] https://github.com/pypa/pip/issues/4022