Upgraded Jenkins and most of the plugins in unrelated work to get pipeline/groovy working. Updated P4 plugin to latest and got below error. Read the bug reports and rolled it back to 1.6. Still getting this error.

Strangely, in one of the builds, it appears to have pulled all the files out of Perforce and barfed at the end. In another, it just would not start.

P4 Task: saving built changes.
FATAL: null
java.lang.NullPointerException
at org.jenkinsci.plugins.p4.tagging.TagAction.getLastChange(TagAction.java:205)
at org.jenkinsci.plugins.p4.PerforceScm.calculateChanges(PerforceScm.java:476)
at org.jenkinsci.plugins.p4.PerforceScm.checkout(PerforceScm.java:434)
at hudson.scm.SCM.checkout(SCM.java:495)
at hudson.model.AbstractProject.checkout(AbstractProject.java:1212)
at hudson.model.AbstractBuild$AbstractBuildExecution.defaultCheckout(AbstractBuild.java:560)
at jenkins.scm.SCMCheckoutStrategy.checkout(SCMCheckoutStrategy.java:86)
at hudson.model.AbstractBuild$AbstractBuildExecution.run(AbstractBuild.java:485)
at hudson.model.Run.execute(Run.java:1735)
at hudson.model.FreeStyleBuild.run(FreeStyleBuild.java:43)
at hudson.model.ResourceController.execute(ResourceController.java:97)
at hudson.model.Executor.run(Executor.java:415)
Finished: FAILURE