In this moment a push to a branch without a config.yml will lead to an error message, but IMHO it should be something less fatal (e.g. Skipped). I have a bunch of repositories with gh-pages branch that always shows as failed with very low interest.
#!/bin/sh -eo pipefail # No configuration was found in your project. Please refer to https://circleci.com/docs/2.0/ to get started with your configuration. false Exited with code 1