can't use the sandbox (-s) option of do-release-upgrade / update-manager

[Wim Lewis]

Tried to do an upgrade in "sandbox" mode using the -s option. It failed to set up the sandbox (though it didn't give a detailed error why). Same behavior with either do-release-upgrade or update-manager.

ubuntu-release-upgrader-core:
  Installed: 1:0.220.8
  Candidate: 1:0.220.8
  Version table:
 *** 1:0.220.8 0
        500 http://us.archive.ubuntu.com/ubuntu/ trusty-updates/main amd64 Packages
        100 /var/lib/dpkg/status
     1:0.220.2 0
        500 http://us.archive.ubuntu.com/ubuntu/ trusty/main amd64 Packages

Distributor ID: Ubuntu
Description: Ubuntu 14.04.5 LTS
Release: 14.04
Codename: trusty

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: ubuntu-release-upgrader-core 1:0.220.8
ProcVersionSignature: Ubuntu 3.19.0-66.74~14.04.1-generic 3.19.8-ckt22
Uname: Linux 3.19.0-66-generic x86_64
ApportVersion: 2.14.1-0ubuntu3.21
Architecture: amd64
CrashDB: ubuntu
Date: Thu Aug 18 12:43:51 2016
DistributionChannelDescriptor:
 # This is a distribution channel descriptor
 # For more information see http://wiki.ubuntu.com/DistributionChannelDescriptor
 canonical-oem-somerville-trusty-amd64-osp1-20150720-0
InstallationDate: Installed on 2016-04-15 (125 days ago)
InstallationMedia: Ubuntu 14.04 "Trusty" - Build amd64 LIVE Binary 20150720-04:06
PackageArchitecture: all
SourcePackage: ubuntu-release-upgrader
UpgradeStatus: Upgraded to trusty on 2016-08-18 (0 days ago)
VarLogDistupgradeTermlog: