$ git clone -n https://src.fedoraproject.org/rpms/alglib.git /var/lib/mock/f40-build-2194995-51510/root/chroot_tmpdir/scmroot/alglib
Cloning into '/var/lib/mock/f40-build-2194995-51510/root/chroot_tmpdir/scmroot/alglib'...
$ git fetch origin ffe1896e0a332c287a0dcd1a1d076003d2285e13:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/alglib
 * [new ref]         ffe1896e0a332c287a0dcd1a1d076003d2285e13 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at ffe1896 Update to 4.01.0