NPE in check working directory action

The Directory project group on vmbuild shows errors in four of the eight scm urls. See INFRA-2037.

Example SCM result:
http://vmbuild.apache.org/continuum/scmResult.action?projectScmRootId=63&projectGroupId=139

SCM result
Project Group Name: Directory
SCM Root URL: scm:svn:http://svn.apache.org/repos/asf/directory/apacheds/trunk
State: Error
SCM Error

Exception:
org.codehaus.plexus.taskqueue.execution.TaskExecutionException: Error executing action 'check-working-directory'
at org.apache.maven.continuum.scm.queue.PrepareBuildProjectsTaskExecutor.performAction(PrepareBuildProjectsTaskExecutor.java:427)
at org.apache.maven.continuum.scm.queue.PrepareBuildProjectsTaskExecutor.updateWorkingDirectory(PrepareBuildProjectsTaskExecutor.java:241)
at org.apache.maven.continuum.scm.queue.PrepareBuildProjectsTaskExecutor.executeTask(PrepareBuildProjectsTaskExecutor.java:148)
at org.codehaus.plexus.taskqueue.execution.ThreadedTaskQueueExecutor$ExecutorRunnable$1.run(ThreadedTaskQueueExecutor.java:116)
at edu.emory.mathcs.backport.java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:442)
at edu.emory.mathcs.backport.java.util.concurrent.FutureTask.run(FutureTask.java:176)
at edu.emory.mathcs.backport.java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:987)
at edu.emory.mathcs.backport.java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:528)
at java.lang.Thread.run(Thread.java:619)
Caused by: java.lang.NullPointerException
at org.apache.maven.continuum.core.action.CheckWorkingDirectoryAction.execute(CheckWorkingDirectoryAction.java:66)
at org.apache.maven.continuum.scm.queue.PrepareBuildProjectsTaskExecutor.performAction(PrepareBuildProjectsTaskExecutor.java:418)
... 8 more