I'm running this line which used to work as expected in Pharo 8, but doesn't in Pharo 9/10:
./pharo bootstrap.image metacello install tonel://./src BaselineOfPowerlang --groups=base
Instead of installing the base group, in Pharo 9 it installs everything (the dev group), so I guess the cli API changed. The baseline is in the Powerlang repo.