$ git clone -n https://src.fedoraproject.org/rpms/gnome-shell.git /var/lib/mock/f40-build-1931818-25123/root/chroot_tmpdir/scmroot/gnome-shell
Cloning into '/var/lib/mock/f40-build-1931818-25123/root/chroot_tmpdir/scmroot/gnome-shell'...
$ git fetch origin 50fc3fd3bea28503342814a1ac645121b0374e3f:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/gnome-shell
 * [new ref]         50fc3fd3bea28503342814a1ac645121b0374e3f -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 50fc3fd Update to 46.4