I am getting this stack trace when I start pyramid pserve:
% python $(which pserve) ../etc/development.ini Traceback
I set the PYTHONPATH to '.' and that solved it for me.
PYTHONPATH
'.'
export PYTHONPATH='.'
For a one-liner you could as easily do:
PYTHONPATH='.' your_python_script
These commands are expected to be run in a terminal