Incorrect parsing of url-encoded parameters

When retreiving url-encoded values in the querystring that for example contains the value %u0448, the parser throws an error. There is no way to capture and resolve these failures within the rubycode, causing hard failures to for example a front-end nginx.

Proposed solution:
Let all errors through and let the backend handle the problem.

To reproduce:

require 'thin'
require 'thin_parser'

class ThinTest < Test::Unit::TestCase

context "with broken thin parser" do should "not raise an error when parsing a faulty url" do request = Rack::MockRequest.new($app)

  request_headers = "GET /abc/123%x{} HTTP/1.1"
  request_headers.gsub!(/\r/, "")
  request_headers.gsub!(/\n/, "\r\n")
  request_headers << "\r\n";

  x = {'rack.input' => StringIO.new}
  assert_nothing_raised Thin::InvalidRequest do
    Thin::HttpParser.new.execute(x, request_headers, 0)
  end
end
should "raise an error when parsing a url with %u0448 in it" do
  request = Rack::MockRequest.new($app)

  request_headers = "GET /abc/123?a=%u0448 HTTP/1.1"
  request_headers.gsub!(/\r/, "")
  request_headers.gsub!(/\n/, "\r\n")
  request_headers << "\r\n";

  x = {'rack.input' => StringIO.new}
  assert_nothing_raised Thin::InvalidRequest do
    Thin::HttpParser.new.execute(x, request_headers, 0)
  end
end

end end