>    The docstring says X is (n_samples, n_features) but from what I can see
>    the scipy_func needs a condensed distance matrix.

Actually, if you look in the scipy.cluster.hierarchy.linkage docstring,
you will see that this format is also accepted.

That said, your remark is very relevant, because we want to enable
multiple possible distance metrics, and we will need to figure how to do
this.