$ git clone -n https://src.fedoraproject.org/rpms/ghc-haxr.git /var/lib/mock/f39-build-1939444-43150/root/chroot_tmpdir/scmroot/ghc-haxr
Cloning into '/var/lib/mock/f39-build-1939444-43150/root/chroot_tmpdir/scmroot/ghc-haxr'...
$ git fetch origin ce7c0e8ee6c4d68227f852a36f70b2f2079f8060:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/ghc-haxr
 * [new ref]         ce7c0e8ee6c4d68227f852a36f70b2f2079f8060 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at ce7c0e8 https://hackage.haskell.org/package/haxr-3000.11.5/changelog