$ git clone -n https://src.fedoraproject.org/rpms/coreutils.git /var/lib/mock/f42-build-861852-170452/root/chroot_tmpdir/scmroot/coreutils
Cloning into '/var/lib/mock/f42-build-861852-170452/root/chroot_tmpdir/scmroot/coreutils'...
$ git fetch origin ddff633d0f852db9dc74c6ea6c81a51fd383901e:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/coreutils
 * [new ref]         ddff633d0f852db9dc74c6ea6c81a51fd383901e -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at ddff633 Switch to upstream version of nproc affinity mask fix (rhbz#2325167)