[libvirt] 5.6.0 regression: "Some activation file descriptors are unclaimed"

After upgrading to v5.6.0, starting libvirtd fails with the following message in journalctl -xe: libvirtd[186338]: internal error: Some activation file descriptors are unclaimed 5b8569dd6e284b9159c701e8bffafb196983fc4a introduces the message. The commit message indicates that systemd version 227 is required, but my system seems to be running version 237. Is this a known issue? Is there any other configuration for systemd needed to avoid the problem? Thanks, John