$ git clone -n https://src.fedoraproject.org/rpms/snapshot.git /var/lib/mock/f40-build-2626225-65251/root/chroot_tmpdir/scmroot/snapshot
Cloning into '/var/lib/mock/f40-build-2626225-65251/root/chroot_tmpdir/scmroot/snapshot'...
$ git fetch origin 7b3989d1f8735701873a7a97dba5aadbd8bb4959:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/snapshot
 * [new ref]         7b3989d1f8735701873a7a97dba5aadbd8bb4959 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 7b3989d Rediff #201 patch on 45.2