See the repo contents.
Also there's something not quite right with the published version numbers ... up until the 4th they were being published as 0.19.1, then from the 5th onwards as 0.19.0. This means that dottyLatestNightlyBuild is currently returning 0.19.1-bin-20190904-beba63a-NIGHTLY despite that not being the most recent.
The more recent failures are in test_sbt.