Request._split_url_string() incorrectly handles empty/blank parameters

[rogerm]

Section 3.4.1.3.2 - Parameters Normalization

Item number 3 of the normalization spec sepcifically states that all values must be included, even if they are empty. The call to parse_qs must therefore be changed to set keep_blank_values=False

[zookos]

Wait, don't you mean it must be changed to set keep_blank_values=True?

[zookos]

keep empty params parsed from the URL (closed by edeb9b6)