A few days ago, setuptools 50.0.0 release caused breakage to many projects. SecureDrop package builds was also broken. We use dh-virtualenv tool to build the packages. Initially, we tried to use the experimental build system from dh-virtualenv. We could specify the version of the setuptools to be installed in the virtualenv while creating it.

This approach worked for Xenial builds. As we are working to have proper builds on Focal (still work in progress), that was broken due to the above-mentioned change.

So, we again tried to use Python's venv module itself to create the virtual environment and use the wheels from the /usr/share/python-wheels directory to build the virtual environment. Which works very nicely on Xenial, but on Focal the default setuptools version is 44.0.0, which also failed to install the dependencies.

Now, we are actually getting the setuptools 46.0.0 wheel and replacing the build container's default setuptools wheel. The team spent a lot of time in debugging and finding a proper fix for the package builds. Hopefully, we will not get a similar breakage on the same kind of dependency error soon (the actual package dependencies are pinned via hashes).