I tried running autopkgtest without the python3-pkg-resources and it fails because python3-httpsig has an undeclared dependency on python3-pkg-resources.
autopkgtest [14:03:19]: test run-tests: [----------------------- ImportError while loading conftest '/tmp/autopkgtest.2pZBOi/autopkgtest_tmp/tests/conftest.py'. tests/conftest.py:5: in <module> from pysmartapp.dispatch import Dispatcher /usr/lib/python3/dist-packages/pysmartapp/__init__.py:3: in <module> from pysmartapp.config import ( /usr/lib/python3/dist-packages/pysmartapp/config.py:6: in <module> from .request import Request, Response /usr/lib/python3/dist-packages/pysmartapp/request.py:3: in <module> from httpsig.verify import HeaderVerifier /usr/lib/python3/dist-packages/httpsig/__init__.py:1: in <module> from pkg_resources import get_distribution, DistributionNotFound E ModuleNotFoundError: No module named 'pkg_resources' autopkgtest [14:03:20]: test run-tests: -----------------------] autopkgtest [14:03:20]: test run-tests: - - - - - - - - - - results - - - - - - - - - - run-tests FAIL non-zero exit status 4 autopkgtest [14:03:20]: @@@@@@@@@@@@@@@@@@@@ summary run-tests FAIL non-zero exit status 4 E: Autopkgtest run failed.