$ git clone -n https://src.fedoraproject.org/rpms/appstream.git /var/lib/mock/f42-build-side-1-3507920-46010/root/chroot_tmpdir/scmroot/appstream
Cloning into '/var/lib/mock/f42-build-side-1-3507920-46010/root/chroot_tmpdir/scmroot/appstream'...
$ git fetch origin 42dfc7d455b24bd8b161c59cb3965f02fdfff40d:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/appstream
 * [new ref]         42dfc7d455b24bd8b161c59cb3965f02fdfff40d -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 42dfc7d Change appstream-data to a conditional Requires: