The specification states that WebRetriever should default the protocol, or the scheme in the language of the governing RFCs,3 to HTTP. Some exploration during the newly enabled manual test revealed that this feature was not yet implemented. Being next on the list and proven to be missing, I proceeded to implement this feature.
3. RFC 1630 first defined URLs, URNs, and URIs. Various refinements culminated in RFC 3986 in 2005, which is the current governing specification as of this writing.