title: Curl setting Content-Type incorrectly
body: <p>I am running a curl operation on the command line and am having trouble forcing the header to set as XML. I use the -H option to force the Content-Type to be xml, however, once I run the command I can see that the header is sent as urlencoded which is tainting one of the data values that I'm sending. Can someone explain to me why the Content-Type is always reset back to "application/x-www-form-urlencoded" instead of "application/atom+xml"?</p>
  
  <p>I am using this to  retrieve an upload token from YouTube using their API. I have no trouble retrieving an authentication token using a similar command. </p>
  
  <pre><code>curl -S -v 
  --location http://gdata.youtube.com/action/GetUploadToken
  -H Content-Type= text/xml
  --data content=some xml content here
  --data GoogleLogin auth="DQAAAHU.....TiU95NXYSLFFENTbNQUy....NjfFoC0nyEKaz-ejEkA_w"
  -H X-Gdata-Key: key=AI39si5EQyo-_L......78eL80r-MooHXtrA48R82AShoQ
  -H Content-Length=445
  </code></pre>