With Git feature branch workflow, when do you update the master branch?
if the tests aren't passing and the newly updated master won't get released into production,
You can update an ephemeral QA/integration branch first, running the test, and update master if those test pass (and trigger the release into production)
"ephemeral" means: you create/reset the QA branch just for integrating the feature branches marked as being for the next release.
You can see an example of ephemeral branches in the git workflow.