Only read headers for download style endpoints.

Author: qimingyuan

Dropbox.Api/Dropbox.Api.nuspec

@@ -2,7 +2,7 @@
 <package >
   <metadata>
     <id>$id$</id>
-    <version>2.2.2</version>
+    <version>2.2.3</version>
     <title>Dropbox v2 API Beta</title>
     <authors>Dropbox Inc</authors>
     <owners>Dropbox Inc</owners>

Dropbox.Api/DropboxRequestHandler.cs

@@ -352,13 +352,16 @@ private async Task<Result> RequestJsonString(
                 request.Headers.TryAddWithoutValidation("Dropbox-Api-Select-User", this.selectUser);
             }
 
+            var completionOption = HttpCompletionOption.ResponseContentRead;
+
             switch (routeStyle)
             {
                 case RouteStyle.Rpc:
                     request.Content = new StringContent(requestArg, Encoding.UTF8, "application/json");
                     break;
                 case RouteStyle.Download:
                     request.Headers.Add(DropboxApiArgHeader, requestArg);
+                    completionOption = HttpCompletionOption.ResponseHeadersRead;
                     break;
                 case RouteStyle.Upload:
                     request.Headers.Add(DropboxApiArgHeader, requestArg);
@@ -378,7 +381,7 @@ private async Task<Result> RequestJsonString(
             }
 
             var disposeResponse = true;
-            var response = await this.options.HttpClient.SendAsync(request);
+            var response = await this.options.HttpClient.SendAsync(request, completionOption);
 
             try
             {