$ git clone -n https://src.fedoraproject.org/rpms/postfix.git /var/lib/mock/f40-build-780136-130690/root/chroot_tmpdir/scmroot/postfix
Cloning into '/var/lib/mock/f40-build-780136-130690/root/chroot_tmpdir/scmroot/postfix'...
$ git fetch origin 5494e96544265abf0c989184ac3e0bd8b29ba1d8:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/postfix
 * [new ref]         5494e96544265abf0c989184ac3e0bd8b29ba1d8 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 5494e96 Rebuild for ICU 74