Debian is special.
They compile more modules statically into libpython.so than a regular build from source does. As a consequence, the modules are not available as dynamically loadable extensions. Issue
#4deals with this problem. The remedy is to add the source of the Modules to the stackless_installer.tar.gz and compile missing modules during the installation using distutils.
Debian and AFAIK Ubuntu nowadays added another complication. It is called MULTIARCH support and modifies the way python computes sys.path and extends the list of module search suffixes (see imp.get_suffixes()). The sys.path case was fixed in issue
#2and then broken again by the fix for issue #4. Currently I'm testing a patch to fix both sys.path and the extended extension list.
The patch works as expected. New installer archives are uploaded.
To update Stackless, force pip to reinstall "stackless-python":
pip install -I stackless-python