InstallationManagerService should not allow duplicate module paths

MSC000001: Failed to start service jboss.patching.manager: org.jboss.msc.service.StartException in service jboss.patching.manager: java.lang.IllegalStateException: Duplicate layer 'base'
	at org.jboss.as.patching.installation.InstallationManagerService.start(InstallationManagerService.java:106)
	at org.jboss.msc.service.ServiceControllerImpl$StartTask.startService(ServiceControllerImpl.java:1736)
	at org.jboss.msc.service.ServiceControllerImpl$StartTask.execute(ServiceControllerImpl.java:1698)
	at org.jboss.msc.service.ServiceControllerImpl$ControllerTask.run(ServiceControllerImpl.java:1556)
	at org.jboss.threads.ContextClassLoaderSavingRunnable.run(ContextClassLoaderSavingRunnable.java:35)
	at org.jboss.threads.EnhancedQueueExecutor.safeRun(EnhancedQueueExecutor.java:1985)
	at org.jboss.threads.EnhancedQueueExecutor$ThreadBody.doRunTask(EnhancedQueueExecutor.java:1487)
	at org.jboss.threads.EnhancedQueueExecutor$ThreadBody.run(EnhancedQueueExecutor.java:1378)
	at java.lang.Thread.run(Thread.java:748)
Caused by: java.lang.IllegalStateException: Duplicate layer 'base'
	at org.jboss.as.patching.installation.LayersFactory$ProcessedLayers.addLayer(LayersFactory.java:305)
	at org.jboss.as.patching.installation.LayersFactory.processRoot(LayersFactory.java:182)
	at org.jboss.as.patching.installation.LayersFactory.process(LayersFactory.java:127)
	at org.jboss.as.patching.installation.LayersFactory.load(LayersFactory.java:86)
	at org.jboss.as.patching.installation.InstallationManagerImpl.<init>(InstallationManagerImpl.java:47)
	at org.jboss.as.patching.installation.InstallationManager.load(InstallationManager.java:185)
	at org.jboss.as.patching.installation.InstallationManagerService.load(InstallationManagerService.java:128)
	at org.jboss.as.patching.installation.InstallationManagerService.start(InstallationManagerService.java:63)
	... 8 more