fix: duplicated query params by follow_redirect

When the original request has query and the server returns redirection
response with Location, HTTPClient wrongly adds query to the new URI. In
such case the Location header could include query part;

e.g.
  http://originalhost/api/call?limit=10
  -> Location: http://otherhost/api/call?limit=10

HTTPClient should just hit the new location '/api/call?limit=10' not
'/api/call?limit=10&limit=10'. Closes #236.