$ git clone -n https://src.fedoraproject.org/rpms/libSM.git /var/lib/mock/f40-build-2008423-45372/root/chroot_tmpdir/scmroot/libSM
Cloning into '/var/lib/mock/f40-build-2008423-45372/root/chroot_tmpdir/scmroot/libSM'...
$ git fetch origin 571cf82ba8d939779a448bbb9f50232fc7010c34:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/libSM
 * [new ref]         571cf82ba8d939779a448bbb9f50232fc7010c34 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 571cf82 libSM 1.2.4