War class loader fails to delegate on redeployment

Just copying an ear with a war (testsuite/output/lib/form-auth.ear) twice to the server deploy directory results in a failure like the following. All subsequent copy/redeployment attempts fail in the same way.

07:32:52,155 ERROR [AbstractKernelController] Error installing to Real: name=vfsfile:/Users/svn/JBossHead/jboss-head/build/output/jboss-5.0.0.CR1/server/cts/deploy/form-auth.ear state=PreReal mode=Manual requiredState=Real
org.jboss.deployers.spi.DeploymentException: Error during deploy: vfsfile:/Users/svn/JBossHead/jboss-head/build/output/jboss-5.0.0.CR1/server/cts/deploy/form-auth.ear/form-auth.war
at org.jboss.deployers.spi.DeploymentException.rethrowAsDeploymentException(DeploymentException.java:49)
at org.jboss.deployers.plugins.deployers.DeployerWrapper.deploy(DeployerWrapper.java:180)
at org.jboss.deployers.plugins.deployers.DeployersImpl.doInstallParentFirst(DeployersImpl.java:946)
at org.jboss.deployers.plugins.deployers.DeployersImpl.doInstallParentFirst(DeployersImpl.java:999)
at org.jboss.deployers.plugins.deployers.DeployersImpl.install(DeployersImpl.java:887)
at org.jboss.dependency.plugins.AbstractControllerContext.install(AbstractControllerContext.java:327)
at org.jboss.dependency.plugins.AbstractController.install(AbstractController.java:1324)
at org.jboss.dependency.plugins.AbstractController.incrementState(AbstractController.java:734)
at org.jboss.dependency.plugins.AbstractController.resolveContexts(AbstractController.java:862)
at org.jboss.dependency.plugins.AbstractController.resolveContexts(AbstractController.java:784)
at org.jboss.dependency.plugins.AbstractController.change(AbstractController.java:622)
at org.jboss.dependency.plugins.AbstractController.change(AbstractController.java:411)
at org.jboss.deployers.plugins.deployers.DeployersImpl.process(DeployersImpl.java:579)
at org.jboss.deployers.plugins.main.MainDeployerImpl.process(MainDeployerImpl.java:541)
at org.jboss.system.server.profileservice.hotdeploy.HDScanner.scan(HDScanner.java:290)
at org.jboss.system.server.profileservice.hotdeploy.HDScanner.run(HDScanner.java:221)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:417)
at java.util.concurrent.FutureTask$Sync.innerRunAndReset(FutureTask.java:280)
at java.util.concurrent.FutureTask.runAndReset(FutureTask.java:135)
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$101(ScheduledThreadPoolExecutor.java:65)
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.runPeriodic(ScheduledThreadPoolExecutor.java:142)
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:166)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:650)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:675)
at java.lang.Thread.run(Thread.java:613)
Caused by: java.lang.NoClassDefFoundError: javax/servlet/http/HttpServlet
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClass(ClassLoader.java:675)
at org.jboss.classloader.spi.base.BaseClassLoader.access$200(BaseClassLoader.java:63)
at org.jboss.classloader.spi.base.BaseClassLoader$2.run(BaseClassLoader.java:502)
at org.jboss.classloader.spi.base.BaseClassLoader$2.run(BaseClassLoader.java:462)
at java.security.AccessController.doPrivileged(Native Method)
at org.jboss.classloader.spi.base.BaseClassLoader.loadClassLocally(BaseClassLoader.java:460)
at org.jboss.classloader.spi.base.BaseClassLoader.loadClassLocally(BaseClassLoader.java:437)
at org.jboss.classloader.spi.base.BaseDelegateLoader.loadClass(BaseDelegateLoader.java:134)
at org.jboss.classloader.spi.filter.FilteredDelegateLoader.loadClass(FilteredDelegateLoader.java:131)
at org.jboss.classloader.spi.base.ClassLoadingTask$ThreadTask.run(ClassLoadingTask.java:452)
at org.jboss.classloader.spi.base.ClassLoaderManager.nextTask(ClassLoaderManager.java:254)
at org.jboss.classloader.spi.base.ClassLoaderManager.process(ClassLoaderManager.java:148)
at org.jboss.classloader.spi.base.BaseClassLoaderDomain.loadClass(BaseClassLoaderDomain.java:196)
at org.jboss.classloader.spi.base.BaseClassLoaderDomain.loadClass(BaseClassLoaderDomain.java:1009)
at org.jboss.classloader.spi.base.BaseClassLoader.loadClassFromDomain(BaseClassLoader.java:728)
at org.jboss.classloader.spi.base.BaseClassLoader.loadClass(BaseClassLoader.java:372)
at java.lang.ClassLoader.loadClass(ClassLoader.java:251)
at org.jboss.wsf.container.jboss50.JAXWSDeployerHookPreJSE.getRelevantServlets(JAXWSDeployerHookPreJSE.java:122)
at org.jboss.wsf.container.jboss50.JAXWSDeployerHookPreJSE.isWebServiceDeployment(JAXWSDeployerHookPreJSE.java:98)
at org.jboss.wsf.container.jboss50.ArchiveDeployerHook.deploy(ArchiveDeployerHook.java:84)
at org.jboss.wsf.container.jboss50.AbstractWebServiceDeployer.internalDeploy(AbstractWebServiceDeployer.java:63)
at org.jboss.deployers.spi.deployer.helpers.AbstractRealDeployer.deploy(AbstractRealDeployer.java:50)
at org.jboss.deployers.plugins.deployers.DeployerWrapper.deploy(DeployerWrapper.java:174)
... 23 more
07:32:52,160 WARN [HDScanner] Failed to process changes
org.jboss.deployers.client.spi.IncompleteDeploymentException: Summary of incomplete deployments (SEE PREVIOUS ERRORS FOR DETAILS):

• • • CONTEXTS IN ERROR: Name -> Error

vfsfile:/Users/svn/JBossHead/jboss-head/build/output/jboss-5.0.0.CR1/server/cts/deploy/form-auth.ear -> java.lang.NoClassDefFoundError: javax/servlet/http/HttpServlet

at org.jboss.deployers.plugins.deployers.DeployersImpl.checkComplete(DeployersImpl.java:662)
at org.jboss.deployers.plugins.main.MainDeployerImpl.checkComplete(MainDeployerImpl.java:661)
at org.jboss.system.server.profileservice.hotdeploy.HDScanner.scan(HDScanner.java:291)
at org.jboss.system.server.profileservice.hotdeploy.HDScanner.run(HDScanner.java:221)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:417)
at java.util.concurrent.FutureTask$Sync.innerRunAndReset(FutureTask.java:280)
at java.util.concurrent.FutureTask.runAndReset(FutureTask.java:135)
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$101(ScheduledThreadPoolExecutor.java:65)
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.runPeriodic(ScheduledThreadPoolExecutor.java:142)
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:166)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:650)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:675)
at java.lang.Thread.run(Thread.java:613)