Worked around a bug where the a group child could be leaked

It may happen that a group entry could be leaked, if an
entry is inserted again after it was removed. We now added
logging to detect it better and worked around the issue.

Change-Id: Iaa6dfedddf5bafe0697bd0411b2e5f24982b1160
Fixes: 63717947
Test: add groups and remove / hun children