$ git clone -n https://src.fedoraproject.org/rpms/gnome-flashback.git /var/lib/mock/f42-build-side-110986-59198468-6571762/root/chroot_tmpdir/scmroot/gnome-flashback
Cloning into '/var/lib/mock/f42-build-side-110986-59198468-6571762/root/chroot_tmpdir/scmroot/gnome-flashback'...
$ git fetch origin 50d10c76582f8acd5d39addfc450c802d1042f66:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/gnome-flashback
 * [new ref]         50d10c76582f8acd5d39addfc450c802d1042f66 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 50d10c7 Update to 3.56.0 (rhbz#2362444)