update shows different packages in real/preview run when trying to upgrade base packages from copr

[Mershl]

Host system details

ostree://fedora:fedora/33/x86_64/silverblue
Version: 33.20201026.0 (2020-10-26T00:44:58Z)

rpm-ostree-2020.5-1.fc33.x86_64

Actual behavior

$ rpm-ostree update --preview
1 metadata, 0 content objects fetched; 592 B transferred in 1 seconds; 0 bytes content written
Enabled rpm-md repositories: gloriouseggroll-mesa-aco gloriouseggroll-mesa-aco-i386 rpmfusion-nonfree code copr:copr.fedorainfracloud.org:dawid:better_fonts fedora updates rpmfusion-nonfree-updates fedora-cisco-openh264 rpmfusion-free-updates rpmfusion-free
AvailableUpdate:
       Upgraded: mesa-dri-drivers 20.2.1-2.fc33 -> 20.3.0-20201026.9c1f6ed.fc33
                 mesa-filesystem 20.2.1-2.fc33 -> 20.3.0-20201026.9c1f6ed.fc33
                 mesa-libEGL-devel 20.2.1-2.fc33 -> 20.3.0-20201026.9c1f6ed.fc33
                 mesa-libGL 20.2.1-2.fc33 -> 20.3.0-20201026.9c1f6ed.fc33
                 mesa-libOSMesa 20.2.1-2.fc33 -> 20.3.0-20201026.9c1f6ed.fc33
                 mesa-libglapi 20.2.1-2.fc33 -> 20.3.0-20201026.9c1f6ed.fc33
                 mesa-vulkan-drivers 20.2.1-2.fc33 -> 20.3.0-20201026.9c1f6ed.fc33

$ rpm-ostree update
1 metadata, 0 content objects fetched; 592 B transferred in 1 seconds; 0 bytes content written
Checking out tree 967a4b3... done
Enabled rpm-md repositories: gloriouseggroll-mesa-aco gloriouseggroll-mesa-aco-i386 rpmfusion-nonfree code copr:copr.fedorainfracloud.org:dawid:better_fonts fedora updates rpmfusion-nonfree-updates fedora-cisco-openh264 rpmfusion-free-updates rpmfusion-free
No upgrade available.

Expected behavior

rpm-ostree upgrades the listed available upgrades of update --preview when called with update.

Steps to reproduce it

1.) rpm-ostree update --preview - shows 7 available upgrades.
2.) rpm-ostree update - shows no available upgrades.

[jlebon]

Dupe of #1579.