We require at least one successful build before a PR can be merged. When the PR is created it immediately recognizes the build for the feature branch, which doesn't do anything, so it completes successfully very fast. But it takes a little bit of time for the PR build to kick off. Which allows enough time for someone to merge the PR before the PR build has actually completed. We use Jenkins for our build pipeline.
How can I help avoid merges before the PR build has successfully completed?