$ git clone -n https://src.fedoraproject.org/rpms/nats-server.git /var/lib/mock/f39-build-1812118-41833/root/chroot_tmpdir/scmroot/nats-server
Cloning into '/var/lib/mock/f39-build-1812118-41833/root/chroot_tmpdir/scmroot/nats-server'...
$ git fetch origin 29bbe3a2983dcb015973f5a70669679164abdfab:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/nats-server
 * [new ref]         29bbe3a2983dcb015973f5a70669679164abdfab -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 29bbe3a update to 2.10.5, close rhbz#2246774