$ git clone -n https://src.fedoraproject.org/rpms/usermode.git /var/lib/mock/f40-build-2044374-48705/root/chroot_tmpdir/scmroot/usermode
Cloning into '/var/lib/mock/f40-build-2044374-48705/root/chroot_tmpdir/scmroot/usermode'...
$ git fetch origin a6c93c2abc7df5bed9e8d4c38e4e549035ac4e2d:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/usermode
 * [new ref]         a6c93c2abc7df5bed9e8d4c38e4e549035ac4e2d -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at a6c93c2 drop install variable, already defined in the macro