return_maps not working in clustering.motifs

I am trying to return the maps of the motifs to identify the vertex on the original graph but this exception rises:

Exception                                 Traceback (most recent call last)
<ipython-input-292-1c9ba08feccd> in <module>
----> 1 motifs, counts = graph_tool.clustering.motifs(g,3,return_maps=True)
      2 motifs

/usr/lib/python3/dist-packages/graph_tool_hack/graph_tool/clustering/__init__.py in motifs(g, k, p, motif_list, return_maps)
    416         for i, vlist in enumerate(vertex_maps):
    417             sub = sub_list[i]
--> 418             vertex_maps[i] = [PropertyMap(vm, sub, "v") for vm in vlist]
    419         return sub_list, hist, vertex_maps
    420     return sub_list, hist

/usr/lib/python3/dist-packages/graph_tool_hack/graph_tool/clustering/__init__.py in <listcomp>(.0)
    416         for i, vlist in enumerate(vertex_maps):
    417             sub = sub_list[i]
--> 418             vertex_maps[i] = [PropertyMap(vm, sub, "v") for vm in vlist]
    419         return sub_list, hist, vertex_maps
    420     return sub_list, hist

/usr/lib/python3/dist-packages/graph_tool_hack/graph_tool/__init__.py in __init__(self, pmap, g, key_type)
    388     def __init__(self, pmap, g, key_type):
    389         if type(self) == PropertyMap:
--> 390             raise Exception("PropertyMap cannot be instantiated directly")
    391         self.__map = pmap
    392         self.__g = weakref.ref(g)

Exception: PropertyMap cannot be instantiated directly

My code is simply :

motifs, counts = graph_tool.clustering.motifs(g,3,return_maps=True)

(g has vertex properties)