The problem when GitHub organization is configured:

Every day there are several active pull requests, that are being modified after new comments from reviewers.

At the same time Jenkins is building these pull requests and branches. All the executors are busy and there is a queue of waiting builds.

Pretty often, after new commits, new build is started in a pull request, while previous build is still running. New build has to wait for the unfinished build to complete before it can start. This makes developers wait more and wastes jenkins recourses.

New build in pull request should abort unneeded previous builds in progress. This should happen when new build goes to the queue, long before it reaches next available executor.

This behavior should not apply to branch builds. This would make a long series of aborted builds on master during hot development days.