Build package from copr dist-git.

$ sudo dnf copr enable praiskup/copr-builder
$ sudo dnf install copr-builder
$ copr-builder --copr      praiskup/ping \
               --package   quick-package \
               --revision  5ce6ec838e22d

We heavily depend on `rpkg` for working with `dist-git`, on `copr-cli` package
to obtain mock profile and on mock to do all the work.  Please make sure to have
properly configured mock.

(motivation https://bugzilla.redhat.com/show_bug.cgi?id=1410403)