How we check if a schema is local or online

From #137

The change to if schema_url.startswith("http") needs to be carried over. It's necessary to "fix(custom_jsonref_jsonloader): Read from filesystem if schema_url is a file path", because lib-cove has already messed around with the uri value by this point (IIRC), and checking schema_url directly is the only way to know if the URL is a file path or not.

Edit: Indeed - uri is parsed, and then uri is set to uri = urljoin(schema_url, ...). So, if schema_url is a file path, then "http" in uri_info.scheme will be True, even though the subsequent GET request will use a value of uri that's prefixed with a file path (i.e. no scheme). So, it's necessary to check schema_url instead of uri. This is more correct, even if this particular test doesn't need it.

@jpmckinney How important do you think it is to do this one? And is it for the purposes of making tests easier or does it affect normal running? I know the number of lines of code changed is tiny, but I would want to fully understand the code path and other things that use this so it may take a while to do.

For reference, change to libcove/lib/common.py, custom_jsonref_jsonloader func, inner jsonloader func:

if "http" in uri_info.scheme:

To

 schema_url.startswith("http")

[jpmckinney]

Hmm, thanks to #136 I circumvent this issue entirely, so I don't need this fixed.

That said, I would keep the issue open, as it is a bug, and for my part, I've confirmed that the fix doesn't negatively affect any other code paths, etc.

The code paths are quite gnarly as this code is very much action-at-a-distance, so I understand that it would take time to re-validate.