Provide a new script for introspecting and recording buildroot metadata

[praiskup]

Currently, #1393 uses specific rpm -q --qf and dnf repoquery commands for introspecting the buildroot (useful for later buildroot reproducibility).

It would be nice to have a python tool using the python3-rpm (or python3-dnf) library instead. The tricky part here would be to use the appropriate version of this library -- we must use the RPM stack from bootstrap, not from host or from buildroot, if bootstrap feature is used.

We could have a drop-in executable script, copy-pasted into the bootstrap by Mock and then executed, but such a script will be precedent definitely.

[praiskup]

We could have a drop-in executable script, copy-pasted into the bootstrap by Mock and then executed

The experiment would be relatively trivial:

import rpm
if __name__ == '__main__':
    rpm.addMacro("_dbpath", "/var/lib/mock/fedora-rawhide-x86_64-bootstrap/root/var/lib/rpm")
    ts = rpm.ts()
    for h in ts.dbMatch():
        print(h["name"])

It is not common to have python3-rpm installed in bootstrap chroot, though. Especially nowadays when the world is switching towards DNF5.

[praiskup]

It feels to me that this isn't the right way (we probably don't want to install python3-rpm into every bootstrap to make this work). Feel free to reopen this if you think otherwise.