Ubuntu 18.10->19.04 upgrade disables HDMI output and ssh during upgrade

[Damiön la Bagh]

What Happened:
When upgrading from 18.10 -> 19.04 about 10 minutes into the upgrade a dialog box shows up to remove old packages at this point the HDMI output and ssh servers are disabled so the only way to continue the upgrade is to physically go to the machine and plug in a VGA cable to an old monitor.

What should have happened:
Current Display output (In this case HDMI) and ssh access should be maintained during an upgrade of a system. Especially when there are user prompts.

Distributor ID: Ubuntu
Description: Ubuntu 19.04
Release: 19.04
Codename: disco

ubuntu-release-upgrader-gtk:
  Geïnstalleerd: 1:19.04.16.1
  Kandidaat: 1:19.04.16.1

See here HDMI has been disconnected through software. The physical connection hadden't been touched. And even after unplugging and re-plugging the HDMI cable the result is the same.

xrandr
Screen 0: minimum 320 x 200, current 1280 x 1024, maximum 8192 x 8192
DP-1 disconnected (normal left inverted right x axis y axis)
HDMI-1 disconnected (normal left inverted right x axis y axis)
DP-2 connected primary 1280x1024+0+0 (normal left inverted right x axis y axis) 376mm x 301mm
   1280x1024 60.02*+ 75.02
   1152x864 75.00
   1024x768 75.03 70.07 60.00
   832x624 74.55
   800x600 72.19 75.00 60.32 56.25
   640x480 75.00 72.81 66.67 59.94
   720x400 70.08
HDMI-2 disconnected (normal left inverted right x axis y axis)
DP-3 disconnected (normal left inverted right x axis y axis)
HDMI-3 disconnected (normal left inverted right x axis y axis)

In settings only one display is shown. Turning the HDMI monitor off then on again with both VGA and HDMI connected restores the display.

ProblemType: Bug
DistroRelease: Ubuntu 19.04
Package: ubuntu-release-upgrader-core 1:19.04.16.1
ProcVersionSignature: Ubuntu 4.18.0-17.18-generic 4.18.20
Uname: Linux 4.18.0-17-generic x86_64
ApportVersion: 2.20.10-0ubuntu27
Architecture: amd64
CrashDB: ubuntu
CurrentDesktop: ubuntu:GNOME
Date: Sun Apr 21 10:35:43 2019
InstallationDate: Installed on 2019-02-22 (57 days ago)
InstallationMedia: Ubuntu 18.10 "Cosmic Cuttlefish" - Release amd64 (20181017.3)
PackageArchitecture: all
SourcePackage: ubuntu-release-upgrader
Symptom: ubuntu-release-upgrader
UpgradeStatus: Upgraded to disco on 2019-04-20 (0 days ago)
VarLogDistupgradeTermlog:

[Launchpad Janitor (janitor)]

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