Can I build only 'head' commits of pull requests?



Could you help me with conditionally skipping builds? What I want is builds being run for every change in master branch, and all the feature branches that are parts of open pull requests. Reason: the test suite of a particular project has grown quite large, and takes considerable time to run. With multiple people working on this project, builds in other projects are often blocked by tests of work-in-progress code pushes to feature branches that are likely to fail anyway.

However, the configuration options that I’ve found allow to trigger a build on changes in either a single branch, or all of them. Is there some way to implement this via configuration options, or should I modify my test suite to quit early based on CI_PULL_REQUEST / CIRCLE_BRANCH env variables?