Resolves issue where the dom0 rpm database does not get used on
successive calls to qubes-dom0-update for debian updatevms.
Also resolves "cannot remove .rpmdbold.####" occurrences.
qubesos/qubes-issues#6124
Correctly extract packages from transaction items:
- old (pre DNF 4): iterate over item.installs()
- new (DNF 4+): item.pkg
The old DNF is not supported anymore, so do not care about it.
The https://bugzilla.redhat.com/1650446 is fixed for enough time already
(included in all supported distributions). The workaround for the bug
have two issues:
- may download repository metadata again
- ignores various settings, including proxy, which breaks it in
TemplateVM
This reverts commit 8d7313b928.
