The only way to be sure: CI checks out master, merges the feature branch, and tests that version. If successful, push to origin. If the push fails (because a pa

The only way to be sure: CI checks out master, merges the feature branch, and tests that version. If successful, push to origin. If the push fails (because a parallel pushed happened in between) start from the beginning. The challenge here is that pull request might be tested again and again. It increases the CI load by some factor for large projects.