$ git clone -n https://src.fedoraproject.org/rpms/ghc-digest.git /var/lib/mock/f41-build-side-1-3013731-36910/root/chroot_tmpdir/scmroot/ghc-digest
Cloning into '/var/lib/mock/f41-build-side-1-3013731-36910/root/chroot_tmpdir/scmroot/ghc-digest'...
$ git fetch origin 71a4ee72425286a12ea9fc6a276944a1b9a83b30:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/ghc-digest
 * [new ref]         71a4ee72425286a12ea9fc6a276944a1b9a83b30 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 71a4ee7 buildrequires gcc-c++