With GCP CSR, is it possible to change the default branch for a repository from master to something else? This doesn't have much bearing on functionality other than the branch that's first displayed in the CSR UI. However, it's something I can change in GitHub.
No, you cannot change the default branch from master to something in Google Cloud Source repository. However, a trick that I use to reach my branch in the UI directly is by following this link:
https://source.cloud.google.com/<project-id>/<repo-name>/+/<branch-name>