$ git clone -n https://src.fedoraproject.org/rpms/postfix.git /var/lib/mock/f40-build-2023895-46943/root/chroot_tmpdir/scmroot/postfix
Cloning into '/var/lib/mock/f40-build-2023895-46943/root/chroot_tmpdir/scmroot/postfix'...
$ git fetch origin 629eddff09169a643f8a729672246d6944d2e532:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/postfix
 * [new ref]         629eddff09169a643f8a729672246d6944d2e532 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 629eddf Converted license tag to SPDX