parse_query_parameters behaves differently than Rack::Utils#parse_nested_query

[nladd]

The parse_query_parameters method exhibits behavior different from Rack::Utils#parse_nested_query when receiving a query string containing duplicate keys. Given a params string like "foo=bar&foo=baz", Rack::Utils#parse_nested_query will return the last instance of foo resulting in {"foo" => "baz"}. Given the same parameter string, parse_query_parameters returns the first instance of foo resulting in {"foo" => "bar"}. This difference in behavior causes the Rails check_box form helper to always submit a zero value because of the hidden input rails inserts box the checkbox input.

[mpalmer]

I'm inclined just to gut the vast majority of the code in NestedParams and pass the request body off to Rack::Utils.parse_nested_query. Anyone disagree? It'll be a behaviour change, though, so it won't be a candidate for an actual fix until 2.0.

[jjb]

Sounds fine to me. Looks like it has a decent set of tests, so we could swap out the guts with confidence. @nladd, could you write us a failing test which illustrates the problem?

[mpalmer]

This is getting fixed as part of #137.