$ git clone -n https://src.fedoraproject.org/rpms/fedora-repos.git /var/lib/mock/f38-build-side-42-init-devel-664670-26644/root/chroot_tmpdir/scmroot/fedora-repos
Cloning into '/var/lib/mock/f38-build-side-42-init-devel-664670-26644/root/chroot_tmpdir/scmroot/fedora-repos'...
$ git fetch origin 6ca5a39adeb632eacd19a226cbd2ac13bb63b5f8:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/fedora-repos
 * [new ref]         6ca5a39adeb632eacd19a226cbd2ac13bb63b5f8 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 6ca5a39 Prep for final f38 release by disabling updates-testing.