$ git clone -n https://src.fedoraproject.org/rpms/cyrus-imapd.git /var/lib/mock/f39-build-1457817-33017/root/chroot_tmpdir/scmroot/cyrus-imapd
Cloning into '/var/lib/mock/f39-build-1457817-33017/root/chroot_tmpdir/scmroot/cyrus-imapd'...
$ git fetch origin d6312b4c475830139aa61d135f4bc6fdf0bffbf9:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/cyrus-imapd
 * [new ref]         d6312b4c475830139aa61d135f4bc6fdf0bffbf9 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at d6312b4 New version 3.8.1 (rhbz#2238280)