SCMTriggerCause [1] currently lacks information about the information that triggered the poll. I believe the assumption is that a checkout will be the first thing to be done by the job, but that is not always the case. In our use case, we lock the resource that is doing the build, so there might be a considerable time delta between poll and checkout. So, when the checkout happens, it checkouts a different changeset, causing problems down the line.

Would it be possible to add a changeset field to SCMTriggerCause?

[1] http://javadoc.jenkins.io/hudson/triggers/SCMTrigger.SCMTriggerCause.html