Currently when creating a post pipeline with the github driver we can
only use the push event. This has the drawback that it ignores
protected branches and thus also works speculatively on any branch if
you want to have a generic post pipeline. This imposes problems with
secrets.
So instead using the push event we want to trigger on pull_request
closed events. However this currently doesn't work as we cannot
distinguish between merged and abandoned pull requests. Adding a
merged requirement nicely solves that problem.
Change-Id: I46670c6aa036976c430a6034a6b1da0e23fa9f92
Tobias Henkel