I'm not able to reproduce the warnings you get. I tried three different VMs: Two with VMware and one with Openstack based on the official debian-9.0.2-20170623-openstack-amd64.qcow2 image.
Your test system seems to be different in some way. Reading the source code I can't even imagine how these warnings could have been created, but I'm by no means a Perl expert. Best regards, Frank Nagel
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