This has been fixed and broken again several times in the past[1].  We need a buildbot that runs the tests installed[2].  Antoine, do you have any thoughts about how to set up such a thing?  I'm willing to host it.

[1] I believe there used to be a program that ran the tests installed, from a cronjob on some dedicated machine somewhere.  It also ran a -R run, I think, as well as being part of a job that built the docs.  When the doc building strategy was changed, somewhere in the process of the transition to Python3 (the program was Python2 only, I believe), it seems to have been taken offline completely.

[2] failing when run as root is a separate problem, and less practical to set a buildbot run for, though since my buildbots run in VMs, it is not completely out of the question.