$ git clone -n https://src.fedoraproject.org/rpms/golang-github-emersion-mbox.git /var/lib/mock/f41-build-side-1-3071439-38810/root/chroot_tmpdir/scmroot/golang-github-emersion-mbox
Cloning into '/var/lib/mock/f41-build-side-1-3071439-38810/root/chroot_tmpdir/scmroot/golang-github-emersion-mbox'...
$ git fetch origin 1981960f38b1da5a308efcb055c0d6c9bf43430f:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/golang-github-emersion-mbox
 * [new ref]         1981960f38b1da5a308efcb055c0d6c9bf43430f -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 1981960 Retire old aerc-related libraries. aerc is now vendored.