Is the Adjacency homology attribute defining?

[ahwagner]

In #488 (comment), there was a question about preserving the homology flag for the Adjacency class.

It is unclear if this class conveys any useful information for evaluating an Adjacency, or if it meaningfully changes the semantics of an Adjacency (and should therefore impact the computed digest). This is a community request for use cases where an Adjacency is used differently depending on the value of this attribute.

[ahwagner]

Relevant information in #429.