$ git clone -n https://src.fedoraproject.org/rpms/ghc-NumInstances.git /var/lib/mock/f39-build-1711562-41228/root/chroot_tmpdir/scmroot/ghc-NumInstances
Cloning into '/var/lib/mock/f39-build-1711562-41228/root/chroot_tmpdir/scmroot/ghc-NumInstances'...
$ git fetch origin d7efe696501f2f0afc03c8eb35bd28a82397326b:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/ghc-NumInstances
 * [new ref]         d7efe696501f2f0afc03c8eb35bd28a82397326b -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at d7efe69 bump release