Unregistering namespace succeeds while nodetypes are in use

ERROR: org.modeshape.jcr.RepositoryNodeTypeManager - Node types were read from the system content, and appear to be inconsistent or invalid: admb
org.modeshape.jcr.value.ValueFormatException: Error converting "admb:test" from String to a Name
	at org.modeshape.jcr.value.basic.NameValueFactory.create(NameValueFactory.java:148)
	at org.modeshape.jcr.value.basic.NameValueFactory.create(NameValueFactory.java:56)
	at org.modeshape.jcr.cache.document.DocumentTranslator.childReferenceFrom(DocumentTranslator.java:942)
	at org.modeshape.jcr.cache.document.DocumentTranslator.childReferencesListFromArray(DocumentTranslator.java:892)
	at org.modeshape.jcr.cache.document.DocumentTranslator.getChildReferences(DocumentTranslator.java:849)
	at org.modeshape.jcr.cache.document.LazyCachedNode.getChildReferences(LazyCachedNode.java:380)
	at org.modeshape.jcr.SystemContent.readAllNodeTypes(SystemContent.java:502)
	at org.modeshape.jcr.RepositoryNodeTypeManager.refreshFromSystem(RepositoryNodeTypeManager.java:732)
	at org.modeshape.jcr.JcrRepository$RunningState.<init>(JcrRepository.java:1124)
	at org.modeshape.jcr.JcrRepository$RunningState.<init>(JcrRepository.java:971)
	at org.modeshape.jcr.JcrRepository.doStart(JcrRepository.java:404)
	at org.modeshape.jcr.JcrRepository.start(JcrRepository.java:328)
	at org.modeshape.jcr.ModeShapeEngine$2.call(ModeShapeEngine.java:370)
	at org.modeshape.jcr.ModeShapeEngine$2.call(ModeShapeEngine.java:365)
	at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303)
	at java.util.concurrent.FutureTask.run(FutureTask.java:138)
	at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
	at java.lang.Thread.run(Thread.java:662)
Caused by: org.modeshape.jcr.value.NamespaceException: There is no namespace registered for the prefix "admb"
	at org.modeshape.jcr.value.basic.NameValueFactory.create(NameValueFactory.java:134)
	... 18 more