Unknown if core or plugin issue.
Had a group of jobs stuck waiting in the queue.
Hovering over them shows triggers and wait time as usual, but no indication of what they're waiting for.

Suspicious log entry:
May 21, 2015 4:43:19 PM hudson.util.DescribableList buildDependencyGraph
SEVERE: Failed to build dependency graph for hudson.model.FreeStyleProject@57fdabe[MyStuckJob]
java.lang.NullPointerException
at hudson.tasks.Fingerprinter$FingerprintAction.getFingerprints(Fingerprinter.java:373)
at hudson.tasks.Fingerprinter$FingerprintAction.getDependencies(Fingerprinter.java:403)
at hudson.tasks.Fingerprinter$FingerprintAction.getDependencies(Fingerprinter.java:390)
at hudson.tasks.Fingerprinter.buildDependencyGraph(Fingerprinter.java:157)
at hudson.util.DescribableList.buildDependencyGraph(DescribableList.java:219)
at hudson.model.Project.buildDependencyGraph(Project.java:207)
at hudson.model.DependencyGraph.build(DependencyGraph.java:95)
at jenkins.model.Jenkins.rebuildDependencyGraph(Jenkins.java:3748)
at jenkins.model.Jenkins$25.call(Jenkins.java:3770)
at jenkins.model.Jenkins$25.call(Jenkins.java:3766)
at java.util.concurrent.FutureTask.run(FutureTask.java:262)
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$201(ScheduledThreadPoolExecutor.java:178)
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:292)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at java.lang.Thread.run(Thread.java:745)

Possibly caused by deleting some other jobs - they weren't supposed to be in the dependency tree, but coincidentally included identical files that were fingerprinted at some point.

Queuing strategy is Weighted Fair Queuing.
Weren't in the queue on startup, unless lack of JENKINS-28486 pulling them in would count.