Removing a Node if the parent is not accessible

currently it's not possible to call Node#remove on a existing, readable node if the
parent is not accessible (even if the editing session had sufficient permission to remove the node).

there exception i got in the test was:
java.lang.IllegalStateException: This builder does not exist: node1
at org.apache.jackrabbit.oak.plugins.memory.MemoryNodeBuilder.write(MemoryNodeBuilder.java:175)
at org.apache.jackrabbit.oak.plugins.memory.MemoryNodeBuilder.removeChildNode(MemoryNodeBuilder.java:294)
at org.apache.jackrabbit.oak.core.TreeImpl.remove(TreeImpl.java:243)
at org.apache.jackrabbit.oak.jcr.delegate.NodeDelegate.remove(NodeDelegate.java:467)