title: Parameter for GET request changed by Python requests
body: <pre><code>params = {'token': 'JVFQ%2FFb5Ri2aKNtzTjOoErWvAaHRHsWHc8x%2FKGS%2FKAuoS4IRJI161l1rz2ab7rovBzGB86bGsh8pmDVaW8jj6AiJ2jT2rLIyt%2Bbpm80MCOE%3D'}
  rsp = requests.get("http://xxxx/access", params=params)
  print rsp.url
  print params
  </code></pre>
  
  <p>when print <code>rsp.url</code>, I get  </p>
  
  <pre><code>http://xxxx/access?token=JVFQ%252FFb5Ri2aKNtzTjOoErWvAaHRHsWHc8x%252FKGS%252FKAuoS4IRJI161l1rz2ab7rovBzGB86bGsh8pmDVaW8jj6AiJ2jT2rLIyt%252Bbpm80MCOE%253D    
  JVFQ%2FF
  JVFQ%252FF
  </code></pre>
  
  <p>The value of the <code>?token=</code> in the url is different from <code>params['token']</code>.<br>
  Why does it change?</p>