$ git clone -n https://src.fedoraproject.org/rpms/gnome-shell.git /var/lib/mock/f42-build-3426564-45188/root/chroot_tmpdir/scmroot/gnome-shell
Cloning into '/var/lib/mock/f42-build-3426564-45188/root/chroot_tmpdir/scmroot/gnome-shell'...
$ git fetch origin 0f2fe1b9167c8c6fcb53947df65b8932c0f7c1aa:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/gnome-shell
 * [new ref]         0f2fe1b9167c8c6fcb53947df65b8932c0f7c1aa -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 0f2fe1b Split gsettings schemas into a -common subpackage