Shortest distance bug

Hello, I found an issue with shortest distance on directed graph that should not be considered as directed.

l = gt.Graph(directed=True)
l.add_edge(0,1)
gt.shortest_distance(l, source=l.vertex(1), directed=False).a

Output:

PropertyArray([2147483647,          0], dtype=int32)

it should be (and it works when creating the graph with directed=False)

PropertyArray([1,          0], dtype=int32)