[2.3] Image download hardlinks the hwe-*-edge as the generic kernel instead of the ga-* kernel.

When I boot a node into 'rescue mode', it is booting into 4.13 kernel.
the maas has no minimum kernel set (globally) nor does the node.

$ maas crash-and-burn maas get-config name=default_min_hwe_kernel
""
$ maas crash-and-burn nodes read
[
...
        "min_hwe_kernel": "",

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: maas 2.3.0-6434-gd354690-0ubuntu1~16.04.1
ProcVersionSignature: Ubuntu 4.4.0-112.135-generic 4.4.98
Uname: Linux 4.4.0-112-generic x86_64
ApportVersion: 2.20.1-0ubuntu2.15
Architecture: amd64
Date: Tue Feb 13 16:54:06 2018
JournalErrors:
 Error: command ['journalctl', '-b', '--priority=warning', '--lines=1000'] failed with exit code 1: Hint: You are currently not seeing messages from other users and the system.
       Users in the 'systemd-journal' group can see all messages. Pass -q to
       turn off this notice.
 No journal files were opened due to insufficient permissions.
PackageArchitecture: all
ProcEnviron:
 TERM=xterm-256color
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: maas
UpgradeStatus: No upgrade log present (probably fresh install)