I wanted to load an existing ontology from my computer by passing IRI to get_ontology and then calling load. It didn't load and when I checked the source code I realized that the problem is that filename does not match the last part of IRI. Example:
ontho_path.append('/path/to/the/dir/with/ontology/inside')
get_ontology('
http://abc.example/ontology.owl').load()
Loading fails with the error that ontology cannot be found online. By debugging I found out that owlready first checked for this ontology locally. Then I found out that when checking locally owlready only matches last part of IRI with a filename. In my case, it was checking if ontology.owl is in the path directory. It was not because I have an ontology with the name ont.owl which contained the correct IRI and should be matched.
I can help with fixing it but the fix would need to open every ontology in the dir to check IRI. Here is the question do we want it. It would be also helpful in case when one ontology imports another by IRI.