$ git clone -n https://src.fedoraproject.org/rpms/ghc-blaze-builder.git /var/lib/mock/f39-build-1507029-35221/root/chroot_tmpdir/scmroot/ghc-blaze-builder
Cloning into '/var/lib/mock/f39-build-1507029-35221/root/chroot_tmpdir/scmroot/ghc-blaze-builder'...
$ git fetch origin 3b45661c48f275f69a3f33247139a728d8ccd34c:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/ghc-blaze-builder
 * [new ref]         3b45661c48f275f69a3f33247139a728d8ccd34c -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 3b45661 bump release