Sometimes the show referring documents box fails to show to correct documents

• Create a new folder with two news articles
• Create a link from news1 to news2 and visa versa
• Now switch between documents, click edit and save and show referring documents
• Repeat previous step in random order a few times

-> Sometimes the referring documents box shows up empty with the following message in the logs:

19.10.2009 17:10:33 ERROR [org.hippoecm.frontend.plugins.reviewedactions.model.ReferringDocumentsProvider.load():132] failed to determine depth of 1108d961-2373-466c-a3d3-8fa4dacd1793: 05a41540-d1a0-4b3b-92d1-b003c0f59c14