[BGL] Bug in isomorphism when the two graphs are of different types

[tiago@…]

The isomorphism implementation checks for the source and target (i, j) of the edge being considered in G2, where it clearly should be G1:

        recur:
        if (iter != ordered_edges.end()) {
          i = source(*iter, G1);
          j = target(*iter, G2);

In the last line, G2 should be G1, otherwise it will not even compile if the graphs have different types of edge descriptors (not to mention it does not make any sense). Note that this is also wrong in the 'literate' documentation provided on the website.

Furthermore the use of "num_vertices" when checking the size of both graphs makes it impossible to use with filtered graphs.

I'm attaching a patch which fixes both these issues.

[tiago@…]

Proposed patch

[Jeremiah Willcock]

(In [82358]) Applied variant of patch from #7845; fixes #7845