Comment 42 for bug 691590

Verification:
The problem
$ sudo chown root:kvm /var/lib/uvtool/libvirt/images/focal-ipxe.qcow
[sudo] password for paelzer:
[✓]─[paelzer@Keschdeichel ~]──[145208]──[12:57 Do Jul 16]──
$ ll /var/lib/uvtool/libvirt/images/focal-ipxe.qcow
-rw------- 1 root kvm 2546794496 Jul 16 12:57 /var/lib/uvtool/libvirt/images/focal-ipxe.qcow
[✓]─[paelzer@Keschdeichel ~]──[145209]──[12:57 Do Jul 16]──
$ virsh start focal-ipxe
Domain focal-ipxe started

[✓]─[paelzer@Keschdeichel ~]──[145210]──[12:57 Do Jul 16]──
$ ll /var/lib/uvtool/libvirt/images/focal-ipxe.qcow
-rw------- 1 libvirt-qemu kvm 2546794496 Jul 16 12:57 /var/lib/uvtool/libvirt/images/focal-ipxe.qcow
[✓]─[paelzer@Keschdeichel ~]──[145211]──[12:57 Do Jul 16]──
$ virsh shutdown focal-ipxe
Domain focal-ipxe is being shutdown

[✓]─[paelzer@Keschdeichel ~]──[145212]──[13:01 Do Jul 16]──
$ ll /var/lib/uvtool/libvirt/images/focal-ipxe.qcow
-rw------- 1 root root 2548105216 Jul 16 13:01 /var/lib/uvtool/libvirt/images/focal-ipxe.qcow

^^ didn't restore original ownership.

Install upgrade:
$ sudo apt install libvirt-daemon-system libvirt-clients
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following package was automatically installed and is no longer required:
  libllvm9
Use 'sudo apt autoremove' to remove it.
The following additional packages will be installed:
  libnss-libvirt libvirt-daemon libvirt-daemon-driver-qemu libvirt-daemon-driver-storage-rbd libvirt0
Suggested packages:
  libvirt-daemon-driver-lxc libvirt-daemon-driver-vbox libvirt-daemon-driver-xen libvirt-daemon-driver-storage-gluster libvirt-daemon-driver-storage-zfs auditd pm-utils systemtap
The following packages will be upgraded:
  libnss-libvirt libvirt-clients libvirt-daemon libvirt-daemon-driver-qemu libvirt-daemon-driver-storage-rbd libvirt-daemon-system libvirt0
7 upgraded, 0 newly installed, 0 to remove and 129 not upgraded.
Need to get 2.907 kB of archives.
After this operation, 0 B of additional disk space will be used.
Do you want to continue? [Y/n] Y
Get:1 http://de.archive.ubuntu.com/ubuntu focal-proposed/universe amd64 libnss-libvirt amd64 6.0.0-0ubuntu8.2 [14,4 kB]
Get:2 http://de.archive.ubuntu.com/ubuntu focal-proposed/main amd64 libvirt-daemon-driver-qemu amd64 6.0.0-0ubuntu8.2 [605 kB]
Get:3 http://de.archive.ubuntu.com/ubuntu focal-proposed/main amd64 libvirt-daemon-driver-storage-rbd amd64 6.0.0-0ubuntu8.2 [28,3 kB]
Get:4 http://de.archive.ubuntu.com/ubuntu focal-proposed/main amd64 libvirt-daemon-system amd64 6.0.0-0ubuntu8.2 [67,5 kB]
Get:5 http://de.archive.ubuntu.com/ubuntu focal-proposed/main amd64 libvirt-clients amd64 6.0.0-0ubuntu8.2 [343 kB]
Get:6 http://de.archive.ubuntu.com/ubuntu focal-proposed/main amd64 libvirt0 amd64 6.0.0-0ubuntu8.2 [1.444 kB]
Get:7 http://de.archive.ubuntu.com/ubuntu focal-proposed/main amd64 libvirt-daemon amd64 6.0.0-0ubuntu8.2 [404 kB]
Fetched 2.907 kB in 2s (1.211 kB/s)
The system does not support apt-btrfs-snapshot
Preconfiguring packages ...
(Reading database ... 384131 files and directories currently installed.)
Preparing to unpack .../0-libnss-libvirt_6.0.0-0ubuntu8.2_amd64.deb ...
Unpacking libnss-libvirt:amd64 (6.0.0-0ubuntu8.2) over (6.0.0-0ubuntu8.1) ...
Preparing to unpack .../1-libvirt-daemon-driver-qemu_6.0.0-0ubuntu8.2_amd64.deb ...
Unpacking libvirt-daemon-driver-qemu (6.0.0-0ubuntu8.2) over (6.0.0-0ubuntu8.1) ...
Preparing to unpack .../2-libvirt-daemon-driver-storage-rbd_6.0.0-0ubuntu8.2_amd64.deb ...
Unpacking libvirt-daemon-driver-storage-rbd (6.0.0-0ubuntu8.2) over (6.0.0-0ubuntu8.1) ...
Preparing to unpack .../3-libvirt-daemon-system_6.0.0-0ubuntu8.2_amd64.deb ...
Unpacking libvirt-daemon-system (6.0.0-0ubuntu8.2) over (6.0.0-0ubuntu8.1) ...
Preparing to unpack .../4-libvirt-clients_6.0.0-0ubuntu8.2_amd64.deb ...
Unpacking libvirt-clients (6.0.0-0ubuntu8.2) over (6.0.0-0ubuntu8.1) ...
Preparing to unpack .../5-libvirt0_6.0.0-0ubuntu8.2_amd64.deb ...
Unpacking libvirt0:amd64 (6.0.0-0ubuntu8.2) over (6.0.0-0ubuntu8.1) ...
Preparing to unpack .../6-libvirt-daemon_6.0.0-0ubuntu8.2_amd64.deb ...
Unpacking libvirt-daemon (6.0.0-0ubuntu8.2) over (6.0.0-0ubuntu8.1) ...
Setting up libvirt0:amd64 (6.0.0-0ubuntu8.2) ...
Setting up libvirt-clients (6.0.0-0ubuntu8.2) ...
Setting up libnss-libvirt:amd64 (6.0.0-0ubuntu8.2) ...
Setting up libvirt-daemon-driver-qemu (6.0.0-0ubuntu8.2) ...
Setting up libvirt-daemon (6.0.0-0ubuntu8.2) ...
Setting up libvirt-daemon-driver-storage-rbd (6.0.0-0ubuntu8.2) ...
Setting up libvirt-daemon-system (6.0.0-0ubuntu8.2) ...
Job failed. See "journalctl -xe" for details.
virtlockd.service is a disabled or a static unit, not starting it.
virtlogd.service is a disabled or a static unit, not starting it.
Setting up libvirt-daemon dnsmasq configuration.
Processing triggers for libc-bin (2.31-0ubuntu9) ...
Processing triggers for man-db (2.9.1-1) ...

Testing again:
$ sudo chown root:kvm /var/lib/uvtool/libvirt/images/focal-ipxe.qcow
[✓]─[paelzer@Keschdeichel ~]──[145223]──[13:04 Do Jul 16]──
$ ll /var/lib/uvtool/libvirt/images/focal-ipxe.qcow
-rw------- 1 root kvm 2548105216 Jul 16 13:01 /var/lib/uvtool/libvirt/images/focal-ipxe.qcow
[✓]─[paelzer@Keschdeichel ~]──[145224]──[13:04 Do Jul 16]──
$ virsh start focal-ipxe
Domain focal-ipxe started

[✓]─[paelzer@Keschdeichel ~]──[145225]──[13:04 Do Jul 16]──
$ ll /var/lib/uvtool/libvirt/images/focal-ipxe.qcow
-rw------- 1 libvirt-qemu kvm 2548105216 Jul 16 13:04 /var/lib/uvtool/libvirt/images/focal-ipxe.qcow
[✓]─[paelzer@Keschdeichel ~]──[145226]──[13:05 Do Jul 16]──
$ virsh shutdown focal-ipxe
Domain focal-ipxe is being shutdown

[✓]─[paelzer@Keschdeichel ~]──[145227]──[13:06 Do Jul 16]──
$ ll /var/lib/uvtool/libvirt/images/focal-ipxe.qcow
-rw------- 1 root kvm 2549481472 Jul 16 13:07 /var/lib/uvtool/libvirt/images/focal-ipxe.qcow

Fix works as intended