I got this NullPointer during a build...

Pproject is a maven 2 job, running "-e install site"

9:12:30 [HUDSON] Archiving site from /data/hudson/experiments/.hudson/jobs/Test_Build_Webchannel/workspace/trunk/service/shipment/shipment-ejb/target/site to /data/hudson/experiments/.hudson/jobs/Test_Build_Webchannel/site/shipment-ejb
19:12:42 [INFO] ------------------------------------------------------------------------
19:12:42 [ERROR] FATAL ERROR
19:12:42 [INFO] ------------------------------------------------------------------------
19:12:42 [INFO] null
19:12:42 [INFO] ------------------------------------------------------------------------
19:12:42 [INFO] Trace
19:12:42 java.lang.NullPointerException
19:12:42 at hudson.remoting.ProxyOutputStream._write(ProxyOutputStream.java:118)
19:12:42 at hudson.remoting.ProxyOutputStream.write(ProxyOutputStream.java:103)
19:12:42 at java.io.BufferedOutputStream.flushBuffer(BufferedOutputStream.java:65)
19:12:42 at java.io.BufferedOutputStream.write(BufferedOutputStream.java:109)
19:12:42 at java.util.zip.DeflaterOutputStream.deflate(DeflaterOutputStream.java:161)
19:12:42 at java.util.zip.DeflaterOutputStream.write(DeflaterOutputStream.java:118)
19:12:42 at java.util.zip.GZIPOutputStream.write(GZIPOutputStream.java:72)
19:12:42 at java.io.BufferedOutputStream.write(BufferedOutputStream.java:105)
19:12:42 at org.apache.tools.tar.TarBuffer.writeBlock(TarBuffer.java:410)
19:12:42 at org.apache.tools.tar.TarBuffer.writeRecord(TarBuffer.java:388)
19:12:42 at hudson.org.apache.tools.tar.TarOutputStream.write(TarOutputStream.java:337)
19:12:42 at hudson.util.io.TarArchiver.visit(TarArchiver.java:103)
19:12:42 at hudson.util.DirScanner$Glob.scan(DirScanner.java:104)
19:12:42 at hudson.FilePath.writeToTar(FilePath.java:1543)
19:12:42 at hudson.FilePath.copyRecursiveTo(FilePath.java:1470)
19:12:42 at hudson.FilePath.copyRecursiveTo(FilePath.java:1399)
19:12:42 at hudson.maven.reporters.MavenSiteArchiver.postExecute(MavenSiteArchiver.java:81)
19:12:42 at hudson.maven.MavenModuleSetBuild$Builder.postExecute(MavenModuleSetBuild.java:828)
19:12:42 at hudson.maven.MavenBuilder$Adapter.postExecute(MavenBuilder.java:300)
19:12:42 at hudson.maven.agent.PluginManagerInterceptor$1MojoIntercepterImpl.callPost(PluginManagerInterceptor.java:170)
19:12:42 at hudson.maven.agent.PluginManagerInterceptor.executeMojo(PluginManagerInterceptor.java:183)
19:12:42 at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoals(DefaultLifecycleExecutor.java:694)
19:12:42 at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoalWithLifecycle(DefaultLifecycleExecutor.java:556)
19:12:42 at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoal(DefaultLifecycleExecutor.java:535)
19:12:42 at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeGoalAndHandleFailures(DefaultLifecycleExecutor.java:387)
19:12:42 at org.apache.maven.lifecycle.DefaultLifecycleExecutor.executeTaskSegments(DefaultLifecycleExecutor.java:348)
19:12:42 at org.apache.maven.lifecycle.DefaultLifecycleExecutor.execute(DefaultLifecycleExecutor.java:180)
19:12:42 at org.apache.maven.lifecycle.LifecycleExecutorInterceptor.execute(LifecycleExecutorInterceptor.java:65)
19:12:42 at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:328)
19:12:42 at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:138)
19:12:42 at org.apache.maven.cli.MavenCli.main(MavenCli.java:362)
19:12:42 at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
19:12:42 at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
19:12:42 at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
19:12:42 at java.lang.reflect.Method.invoke(Method.java:597)
19:12:42 at org.codehaus.classworlds.Launcher.launchEnhanced(Launcher.java:315)
19:12:42 at org.codehaus.classworlds.Launcher.launch(Launcher.java:255)
19:12:42 at hudson.maven.agent.Main.launch(Main.java:165)
19:12:42 at hudson.maven.MavenBuilder.call(MavenBuilder.java:165)
19:12:42 at hudson.maven.MavenModuleSetBuild$Builder.call(MavenModuleSetBuild.java:750)
19:12:42 at hudson.maven.MavenModuleSetBuild$Builder.call(MavenModuleSetBuild.java:694)
19:12:42 at hudson.remoting.UserRequest.perform(UserRequest.java:114)
19:12:42 at hudson.remoting.UserRequest.perform(UserRequest.java:48)
19:12:42 at hudson.remoting.Request$2.run(Request.java:270)
19:12:42 at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:441)
19:12:42 at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303)
19:12:42 at java.util.concurrent.FutureTask.run(FutureTask.java:138)
19:12:42 at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
19:12:42 at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
19:12:42 at java.lang.Thread.run(Thread.java:619)

Build fails after that.