$ git clone -n https://src.fedoraproject.org/rpms/gnome-shell.git /var/lib/mock/f42-build-3340315-44983/root/chroot_tmpdir/scmroot/gnome-shell
Cloning into '/var/lib/mock/f42-build-3340315-44983/root/chroot_tmpdir/scmroot/gnome-shell'...
$ git fetch origin 20d00105d2fa58f1d7184b660eb449eb91d556b8:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/gnome-shell
 * [new ref]         20d00105d2fa58f1d7184b660eb449eb91d556b8 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 20d0010 Update to 48~rc