Description of problem:
xl2tpd explictly Requires: kmod(l2tp_ppp.ko), which is provided by both kernel-modules-extra and kernel-debug-modules-extra.  If kernel-{core,modules} are present and kernel-debug-* not, then the expectation is that kernel-modules-extra would be pulled in instead of all of kernel-debug-{core,modules,modules-extra}.

In short, the virtual provider with the shortest remaining dependency tree should be given priority.

How reproducible:
100%

Steps to Reproduce:
On an system without kernel-debug-* nor kernel-modules-extra installed:
dnf install xl2tpd

Actual results:
kernel-debug-* packages are selected to be installed

Expected results:
kernel-modules-extra should be selected instead, as kernel-core and kernel-modules are already installed and kernel-debug-* are not.

Additional info:
Obviously, a workaround is to install kernel-modules-extra manually prior to or together with xl2tpd (or e.g. NetworkManager-l2tp which Requires: it).

If this can't be fixed in libsolv, can this be worked around with a weak dep in the kernel, or do we need a change to the Packaging guidelines to e.g. Suggests: kernel-modules-extra when Requires: kmod()?