Extending path with identical start and end kmer

[Colelyman]

Currently, the extendPath method will only return the startKmer when startKmer == endKmer. Is this the correct behavior should a bubble be able to be a loop?

I think that a bubble should be able to be a loop, because if the endKmer is the same as the startKmer, then there has to be a path that forms that loop. Furthermore, biologically a loop can suggest an indel in one species that is not present in others.