$ git clone -n https://src.fedoraproject.org/rpms/gnome-flashback.git /var/lib/mock/f40-build-2236147-53493/root/chroot_tmpdir/scmroot/gnome-flashback
Cloning into '/var/lib/mock/f40-build-2236147-53493/root/chroot_tmpdir/scmroot/gnome-flashback'...
$ git fetch origin c401a65787cb611f22e74bd15a4011d6598959be:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/gnome-flashback
 * [new ref]         c401a65787cb611f22e74bd15a4011d6598959be -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at c401a65 https://fedoraproject.org/wiki/Changes/EncourageI686LeafRemoval