$ git clone -n https://src.fedoraproject.org/rpms/oxygen-sounds.git /var/lib/mock/f42-build-side-1-3554937-46650/root/chroot_tmpdir/scmroot/oxygen-sounds
Cloning into '/var/lib/mock/f42-build-side-1-3554937-46650/root/chroot_tmpdir/scmroot/oxygen-sounds'...
$ git fetch origin 2c00f78ac69772d43aa4011f46b19a414da66aa3:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/oxygen-sounds
 * [new ref]         2c00f78ac69772d43aa4011f46b19a414da66aa3 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 2c00f78 6.4.0