$ git clone -n https://src.fedoraproject.org/rpms/nbdkit.git /var/lib/mock/f40-build-2254639-54233/root/chroot_tmpdir/scmroot/nbdkit
Cloning into '/var/lib/mock/f40-build-2254639-54233/root/chroot_tmpdir/scmroot/nbdkit'...
$ git fetch origin 63cf2b755e2639574a4f9a014ec0138fee60bb94:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/nbdkit
 * [new ref]         63cf2b755e2639574a4f9a014ec0138fee60bb94 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 63cf2b7 New upstream development version 1.37.5