Since upgrading to 5.2.1 of the TFS plugin bad things have started happening: Last step in job is to apply label to TFS if all unit tests pass. Instead I get this more often than not:

Creating label 'TPS_1927' on '$/PSD Team/TPS/TPS App' as of the current version in workspace 'Hudson-TPS-MASTER'...
ERROR: Build step failed with exception
java.lang.RuntimeException: java.lang.RuntimeException: Label creation failed.
at hudson.plugins.tfs.model.Server.execute(Server.java:226)
at hudson.plugins.tfs.TFSLabeler.perform(TFSLabeler.java:86)
at hudson.tasks.BuildStepMonitor$2.perform(BuildStepMonitor.java:32)
at hudson.model.AbstractBuild$AbstractBuildExecution.perform(AbstractBuild.java:779)
at hudson.model.AbstractBuild$AbstractBuildExecution.performAllBuildSteps(AbstractBuild.java:720)
at hudson.model.Build$BuildExecution.post2(Build.java:185)
at hudson.model.AbstractBuild$AbstractBuildExecution.post(AbstractBuild.java:665)
at hudson.model.Run.execute(Run.java:1745)
at hudson.model.FreeStyleBuild.run(FreeStyleBuild.java:43)
at hudson.model.ResourceController.execute(ResourceController.java:98)
at hudson.model.Executor.run(Executor.java:404)
Caused by: java.lang.RuntimeException: Label creation failed.
at hudson.plugins.tfs.commands.LabelCommand.call(LabelCommand.java:70)
at hudson.plugins.tfs.commands.LabelCommand.call(LabelCommand.java:22)
at hudson.remoting.LocalChannel.call(LocalChannel.java:45)
at hudson.plugins.tfs.model.Server.execute(Server.java:222)
... 10 more

This is REALLY BAD as we rely on labels to deploy by label via Web Deploy.