As michaelw recently notes in JENKINS-38508, and as we can see in the code, the poll and changelog options combine to determine whether polling happens. This means that polling can still happen even if poll is false – assuming changelog is true, which it is by default.
I'm assuming this is necessary to make the changelog stuff work as expected, but it's pretty confusing from a user's perspective. It took us some time to discover this behavior in a situation where we did not want some repos to be polled.
Assuming there's not a way to make this behavior more explicit in the checkout interface, is it possible that the relationship between poll and changelog could be made clearer, maybe in the README? I can submit a PR if there is interest in this.
Thanks for your work on this important plugin.