This galaxy installation uses supervisord to start. So there is a .venv stanza there and has been from the start - 18.05 was a clean install. I do not quite understand … there seems to be an either/or architecture with conda being incompatible with venv. Also the devs seem to be moving more towards conda.
Then searches indicate problems with individual packages like devutils when they do not uninstall cleanly. Also in the .venv world yarn does not play nicely with npm. It looks like my previous galaxy installation is not upgrading in either the .venv paradigm or the conda paradigm because of some package that cant make way to be reinstalled by the upgrade.
So to answer your question the virtual environment is the one that was created from the original clean install of 18.05.
Would it be OK to remove the package that is causing the installation to fail by file deletion? I dont want to just try this without some reflection.