package docker.io 17.12.1-0ubuntu1 failed to install/upgrade: installed docker.io package post-installation script subprocess returned error exit status 1

[Vadim Dyachenko]

this is on the latest version of Ubuntu on a VM

ProblemType: Package
DistroRelease: Ubuntu 18.04
Package: docker.io 17.12.1-0ubuntu1
ProcVersionSignature: Ubuntu 4.15.0-20.21-generic 4.15.17
Uname: Linux 4.15.0-20-generic x86_64
ApportVersion: 2.20.9-0ubuntu7
Architecture: amd64
Date: Mon May 21 12:50:47 2018
DuplicateSignature:
 package:docker.io:17.12.1-0ubuntu1
 Setting up docker.io (17.12.1-0ubuntu1) ...
 addgroup: The group `docker' already exists and is not a system group. Exiting.
 dpkg: error processing package docker.io (--configure):
  installed docker.io package post-installation script subprocess returned error exit status 1
ErrorMessage: installed docker.io package post-installation script subprocess returned error exit status 1
InstallationDate: Installed on 2018-05-11 (10 days ago)
InstallationMedia: Ubuntu 18.04 LTS "Bionic Beaver" - Release amd64 (20180426)
Python3Details: /usr/bin/python3.6, Python 3.6.5, python3-minimal, 3.6.5-3
PythonDetails: /usr/bin/python2.7, Python 2.7.15rc1, python-minimal, 2.7.15~rc1-1
RelatedPackageVersions:
 dpkg 1.19.0.5ubuntu2
 apt 1.6.1
SourcePackage: docker.io
Title: package docker.io 17.12.1-0ubuntu1 failed to install/upgrade: installed docker.io package post-installation script subprocess returned error exit status 1
UpgradeStatus: No upgrade log present (probably fresh install)