package ubuntu-snappy-cli 1.5ubuntu1 [modified: usr/bin/snappy] failed to install/upgrade: subprocess installed post-installation script returned error exit status 1

[ebnf]

installed ubuntu-desktop-next, purged it as it's not usable even for testing on a desktop, then installed ubuntu-desktop

ProblemType: Package
DistroRelease: Ubuntu 15.10
Package: ubuntu-snappy-cli 1.5ubuntu1
ProcVersionSignature: Ubuntu 4.1.0-3.3-generic 4.1.3
Uname: Linux 4.1.0-3-generic x86_64
ApportVersion: 2.18-0ubuntu6
Architecture: amd64
Date: Wed Aug 12 20:36:25 2015
DuplicateSignature: package:ubuntu-snappy-cli:1.5ubuntu1 [modified: usr/bin/snappy]:subprocess installed post-installation script returned error exit status 1
ErrorMessage: subprocess installed post-installation script returned error exit status 1
InstallationDate: Installed on 2014-10-18 (301 days ago)
InstallationMedia: Ubuntu 14.10 "Utopic Unicorn" - Alpha amd64 (20140923)
RelatedPackageVersions:
 dpkg 1.18.2ubuntu1
 apt 1.0.9.10ubuntu1
SourcePackage: ubuntu-snappy
Title: package ubuntu-snappy-cli 1.5ubuntu1 [modified: usr/bin/snappy] failed to install/upgrade: subprocess installed post-installation script returned error exit status 1
UpgradeStatus: No upgrade log present (probably fresh install)

[Michael Vogt (mvo)]

The error is:
"""
Adding system user `snappypkg' (UID 126) ...
Adding new group `snappypkg' (GID 134) ...
groupadd: cannot lock /etc/group; try again later.
adduser: `/usr/sbin/groupadd -g 134 snappypkg' returned error code 10. Exiting.
""""

We no longer add a "snappypkg" group in 16.04 so this is not an issue anymore.