If I run the build through Jenkins but only 1 at a time, the build is successful. If I run concurrent builds of the same project through Jenkins, I get a NullPointerException from the TestNG plugin.

java.lang.NullPointerException
at hudson.plugins.testng.Publisher.locateReports(Publisher.java:180)
at hudson.plugins.testng.Publisher.perform(Publisher.java:105)
at hudson.tasks.BuildStepMonitor$1.perform(BuildStepMonitor.java:20)
at hudson.model.AbstractBuild$AbstractBuildExecution.perform(AbstractBuild.java:776)
at hudson.model.AbstractBuild$AbstractBuildExecution.performAllBuildSteps(AbstractBuild.java:723)
at hudson.model.Build$BuildExecution.post2(Build.java:183)
at hudson.model.AbstractBuild$AbstractBuildExecution.post(AbstractBuild.java:670)
at hudson.model.Run.execute(Run.java:1763)
at hudson.model.FreeStyleBuild.run(FreeStyleBuild.java:43)
at hudson.model.ResourceController.execute(ResourceController.java:98)
at hudson.model.Executor.run(Executor.java:381)