In V2.3.5 of the git plug-in polling without detecting changes caused a build to run. With V2.3.6 and later this is no longer true.

We think the issue that changed this was:
https://issues.jenkins-ci.org/browse/JENKINS-29066

This, however, is a problem now.

We host our Git repos on Bitbucket (former Stash). Sometimes, we have to invoke "Trigger Build" even when there were no changes pushed to the Git repos. Since that trigger causes a polling for changes, this has no effect anymore with a version newer than V2.3.5.

Why Do We Need This, Anyway?

Build results can depend on external systems. If external systems are not available or not correctly configured, the build results are Failed. Now, if we fix those external systems problems, we want to just re-trigger the job to rebuild again.