title: Jackrabbit Oak merge not saving changes
body: <p>I just started to look into Jackrabbit Oak 1.7.5 and I can't get my changes saved - this test fails on the last assertion: </p>
  
  <pre><code>public class JCRTest {
  
  @Test
  public void testCommit() throws CommitFailedException {
      final NodeStore ns = new MemoryNodeStore();
      final String imagesFolder = "images";
      NodeState rootState = ns.getRoot();
  
      //newly created store does not have nodes
      assertThat(rootState.getChildNode(imagesFolder).exists(), is(equalTo(false)));
  
      NodeBuilder rootBuilder = rootState.builder();
      //adding a node called 'images'
      rootBuilder.child(imagesFolder);
  
      //it is still not going to be shown since we are working in our own 'state'
      assertThat(rootState.getChildNode(imagesFolder).exists(), is(equalTo(false)));
  
      //merging the changes into root
      ns.merge(rootBuilder, EmptyHook.INSTANCE, CommitInfo.EMPTY);
  
      //expecting to see the 'images' folder
      assertThat(rootState.getChildNode(imagesFolder).exists(), is(equalTo(true)));
  }
  }
  </code></pre>