Comment 3 for bug 1960459

Looking at this again, I believe this bug may have been fixed (or at least mitigated) in Sage 9.1, which introduced some changes to the `sage` entrypoint around the `exec` commands I identified in my original report. More specifically the changes introduced by this commit: https://github.com/sagemath/sage/commit/248c13b542b12521bd91d6648bd6220fb7593a26 (tied to this ticket on the sagemath tracker: https://trac.sagemath.org/ticket/29627)

If I change `exec python3` in `/usr/bin/sage` to `exec "$SAGE_PYTHON"/bin/python3` (i.e. apply the changes in the linked commit), sage does load up successfully even if a virtual environment is active (i.e. if `python3` points somewhere other than `/usr/bin/python3`). IPython does still issue a warning about the active venv, but sage is able to successfully start. Not sure if there is any interest in a backport here, or even if this package is under active maintenance in Ubuntu, but thought I'd share some more information about the problem upstream.

I should also note that on 22.04 (sage 9.5), sage does not start when a venv is active, although the error report is substantially longer and it appears to be a separate issue.