Here is a list of P4 plugin issues that I'm also seeing with the Subversion plugin:

		JENKINS-53922	Poll results in changes always found when using 2 global libraries
		JENKINS-44358	the first time scm polling of a job after server restart always return "changes found"

We run nightly builds if there are changes in Subversion to items in the include list (we also use the exclude list). After we restart the Jenkins host, some projects will run a nightly build and list no changes in the change list even though it says there was a change.

Also, we will see a nightly build that failed be triggered the next night and list no changes in the change list. So, no reason to trigger it, but it is triggered anyway. It will keep on failing every night until I get it to succeed at which point it will not be triggered the next night.