def fetch_with_errors(dependency,
                        all               = false,
                        matching_platform = true,
                        prerelease        = false)

    specs_and_sources, errors = find_matching_with_errors(dependency,
                                                          all,
                                                          matching_platform,
                                                          prerelease)

    ss = specs_and_sources.map do |spec_tuple, source_uri|
      [fetch_spec(spec_tuple, URI.parse(source_uri)), source_uri]
    end

    return [ss, errors]
  end
#
Fetch specs matching +dependency+.  If +all+ is true, all matching
(released) versions are returned.  If +matching_platform+ is
false, all platforms are returned. If +prerelease+ is true,
prerelease versions are included.