Even though the changelog.xml file for the build has a changelist in it:

All I see on the build summary page is:

I am using the workflow plugin. The input to the checkout call is:

00:00:01.526 [scm_sync_stream] sync_settings:[$class:PerforceScm, poll:false, credential:7779d639-7544-48ae-83d7-183216a1422f, populate:[$class:ForceCleanImpl, have:true, modtime:false, quiet:false, pin:140731], workspace:[$class:StreamWorkspaceImpl, charset:none, format:jenkins-brhel7ac-scm_test-RE_main, pinHost:false, streamName://RE/main]]

I added some debug output to the workflow and found that the P4ChangeEntry object is missing all of the information, but ChangeLogSet.isEmptSet() returned false:

00:00:09.627 [find_prop] search_list:[files, affectedFiles] obj:org.jenkinsci.plugins.p4.changes.P4ChangeEntry@32605bff obj.prop:[changeTime:2015-09-11 06:19:30, date:Fri Sep 11 18:19:30 CDT 2015, id:null, files:[], commitId:null, msgEscaped:, timestamp:-1, shelved:false, maxLimit:50, msg:, class:class org.jenkinsci.plugins.p4.changes.P4ChangeEntry, jobs:[], msgAnnotated:, fileLimit:false, changeNumber:null, label:false, affectedPaths:[], clientId:, author:null, parent:org.jenkinsci.plugins.p4.changes.P4ChangeSet@5437dc2f]

Also, I am not sure if this is related to the same issue or not, but when there are two checkout calls, it creates to change summary lists and two "Label this build" links on the build summary page.