PR build in VSTS fails: A pull request analysis cannot have the branch analysis parameter 'sonar.branch.name'

I’m running on Linux and using the new SonarSource tasks. According to this page : https://blog.sonarsource.com/sonarcloud-loves-your-build-pipeline:

If you are on Microsoft VSTS , nothing to worry about! The “Prepare Analysis Configuration” task of the SonarCloud extension will set the appropriate properties when your build definition is set as a build validation on the pull requests of your projects.

But that doesn’t seem to be working

Never mind, I was setting setting sonar.branch.name myself, which isn’t necessary.