The IsomorphismTesterTest. testBiphenyl seems to randomly fail. I wrote a quick loop to invoke the test multiple times and tried changing the SMILES to loading mol and cml files. When loading mols/cml (maintaining one molecule with aromatic) the test never fail. It is therefore possible that one of the smiles parsers is causing this fail but not generating the molecule correctly but I don't know. I don't know how we could track down the actually cause of the failure but ideas are welcome.
Another observation is that this test is for UniversalIsomorphismTester and not the IsomorphismTester which the test resides in and should probably be moved.