Experiment with different install mechanism to get coverage

.github/workflows/test.yml

@@ -106,7 +106,8 @@ jobs:
           pip install --upgrade setuptools pip wheel
           pip install --upgrade -r dev-requirements.txt
           python setup.py bdist_wheel
-          pip install dist/*.whl
+          #pip install dist/*.whl
+          pip install -e.
           pip freeze
           # hg-evolve pinned to 9.2 because hg-evolve dropped support for
           # hg 4.5, installed with apt in Ubuntu 18.04