Group transactions should fail on missing non-optional packages

[kontura]

There is a dnf4 PR for this behavior: rpm-software-management/dnf#1848

I think we should finish this long standing change/request and implement it in dnf5.

The group sub-commands should be consistent with the rest of dnf5 commands and it should fail if non-optional packages are missing.

The dnf5 --skip-unavailable flag should be used to proceed in spite of missing packages.

[ppisar]

I'm for this change. I guess the strict handing should apply to environments too.

I'm not sure whether "dnf upgrade" also upgrades group definitions and it should be involved in this change.

[m-blaha]

I recall a situation involving mandatory packages in groups that were specific to certain architectures and did not exist on other arches (see https://bugzilla.redhat.com/show_bug.cgi?id=1427365#c5). If I remember correctly, the issue was addressed by tagging these packages with the arch flag, e.g. <packagereq type="mandatory" arch="i686,x86_64">pkg</packagereq>. On top of that, there is also the basearchonly flag, see https://fedoraproject.org/wiki/How_to_use_and_edit_comps.xml_for_package_groups.

I believe our current implementation of groups based on libsolv lacks support for the arch and basearchonly flags - the parser in libsolv::repo_add_comps() just ignores them. While I do not see these flags used in the current Fedora comps.xml, we should consider this use case as we work on this issue. These flags, particularly arch, are utilized in some popular third-party repositories like rpmfusion.

But otherwise yes, I do support this change.