Cannot install snap package in oem prepare mode - dial tcp: lookup api.snapcraft.io on [::1]:53: read udp [::1]:35268->[::1]:53: read: connection refused

[Jean-Baptiste Lallement]

Ubuntu Xenial Desktop 20180223

Test Case:
1. Do an OEM installation
2. During the preparation stage, install a snap package

Actual result
It fails with
oem@sqfs:~$ snap install ohmygiraffe
error: cannot install "ohmygiraffe": Get
       https://api.snapcraft.io/api/v1/snaps/details/ohmygiraffe?channel=stable&fields=anon_download_url%2Carchitecture%2Cchannel%2Cdownload_sha3_384%2Csummary%2Cdescription%2Cdeltas%2Cbinary_filesize%2Cdownload_url%2Cepoch%2Cicon_url%2Clast_updated%2Cpackage_name%2Cprices%2Cpublisher%2Cratings_average%2Crevision%2Cscreenshot_urls%2Csnap_id%2Clicense%2Cbase%2Csupport_url%2Ccontact%2Ctitle%2Ccontent%2Cversion%2Corigin%2Cdeveloper_id%2Cprivate%2Cconfinement%2Cchannel_maps_list:
       dial tcp: lookup api.snapcraft.io on [::1]:53: read udp
       [::1]:35268->[::1]:53: read: connection refused

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: snapd 2.31.1
ProcVersionSignature: Ubuntu 4.13.0-36.40~16.04.1-generic 4.13.13
Uname: Linux 4.13.0-36-generic x86_64
ApportVersion: 2.20.1-0ubuntu2.15
Architecture: amd64
CurrentDesktop: Unity
Date: Fri Feb 23 14:48:01 2018
InstallationDate: Installed on 2018-02-23 (0 days ago)
InstallationMedia: Ubuntu 16.04.3 LTS "Xenial Xerus" - Release amd64 (20180223)
SourcePackage: snapd
UpgradeStatus: No upgrade log present (probably fresh install)

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.