$ git clone -n https://src.fedoraproject.org/rpms/ghc-sourcemap.git /var/lib/mock/f41-build-840187-160595/root/chroot_tmpdir/scmroot/ghc-sourcemap
Cloning into '/var/lib/mock/f41-build-840187-160595/root/chroot_tmpdir/scmroot/ghc-sourcemap'...
$ git fetch origin ac976b7b976f364708f720fbbff739e355052a9a:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/ghc-sourcemap
 * [new ref]         ac976b7b976f364708f720fbbff739e355052a9a -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at ac976b7 bump release