I created another test to run all tests in Pharo: https://ci.inria.fr/rmod/view/Versions%20and%20Dependencies/job/MetacelloPreview-Pharo2-all-tests/

They are a lot of tests failed in OSProcess but the OSProcess tests are already red: https://ci.inria.fr/pharo-contribution/job/OSProcess/PHARO=20,VERSION=stable,VM=vm/165/testReport/

To summarize, the problem is more on the OSProcess dependency that will come with MetacelloPreview.