I wrote the following extension method to clone the request.
public static HttpRequestMessage Clone(this HttpRequestMessage req)
{
HttpRequestMessage clone = new HttpRequestMessage(req.Method, req.RequestUri);
clone.Content = req.Content;
clone.Version = req.Version;
foreach (KeyValuePair<string, object> prop in req.Properties)
{
clone.Properties.Add(prop);
}
foreach (KeyValuePair<string, IEnumerable<string>> header in req.Headers)
{
clone.Headers.TryAddWithoutValidation(header.Key, header.Value);
}
return clone;
}