title: Strange error about type defined multiple times with PCL
body: <p>I have Xamarin.Android, Xamarin.iOS and Windows Phone 8 applications, both referencing common PCL library. Inside this library I am using HttpClient, and because WP8, I need nuget package <code>Microsoft.Net.Http.2.2.22</code></p>
  
  <p>Without enabling compression on HttpClient everything works fine on all 3 platforms. However, after changing code to </p>
  
  <pre><code>var handler = new HttpClientHandler();
  if (handler.SupportsAutomaticDecompression)
  {
      handler.AutomaticDecompression = DecompressionMethods.GZip | DecompressionMethods.Deflate;
  }
  httpClient = new HttpClient(handler);
  </code></pre>
  
  <p>there is build error with the library on iOS (both Android and WP works fine with this) telling me about multiple definition of <code>DecompressionMethods</code>. What is strange - the second assembly mentioned in error is <code>System.Net.Primitives.dll</code> - which DOES NOT contain definition of DecompressionMethods (i even checked in ILSpy).</p>
  
  <p>Of course, I tried clean solution, rebuild, close/open Xamarin Studio etc... </p>
  
  <p>Error :</p>
  
  <pre><code>MyApiHttpClient.cs(30,50): error CS0433: The imported type  `System.Net.DecompressionMethods' is defined multiple times
  /Users/vtoth/myprototype/Services/CommonServices/../../packages/Microsoft.Net.Http.2.2.22/lib/portable-net40+sl4+win8+wp71+wpa81/System.Net.Http.Primitives.dll (Location of the symbol related to previous error)
  /Library/Frameworks/Mono.framework/Versions/3.2.6/lib/mono/xbuild-frameworks/.NETPortable/v4.5/Profile/Profile49/System.Net.Primitives.dll (Location of the symbol related to previous error)
  Task "Csc" execution -- FAILED
  Done building target "CoreCompile" in project "/Users/vtoth/myprototype/Services/CommonServices/CommonServices.csproj".-- FAILED
  </code></pre>
  
  <p>EDIT:
  Version info about dev environment:</p>
  
  <blockquote>
    <p>=== Xamarin Studio ===</p>
    
    <p>Version 4.2.4 (build 35) Installation UUID:
    (...) Runtime:    Mono 3.2.6
    ((no/9b58377)     GTK+ 2.24.23 (Raleigh theme)</p>
    
    <p>Package version: 302060000</p>
    
    <p>=== Apple Developer Tools ===</p>
    
    <p>Xcode 5.1.1 (5085) Build 5B1008</p>
    
    <p>=== Xamarin.iOS ===</p>
    
    <p>Version: 7.2.1.42 (Business Edition) Hash: 773c77c Branch:  Build
    date: 2014-04-18 15:39:16-0400</p>
    
    <p>=== Xamarin.Mac ===</p>
    
    <p>Xamarin.Mac: Not Installed</p>
    
    <p>=== Xamarin.Android ===</p>
    
    <p>Version: 4.12.3 (Business Edition) Android SDK:
    /Users/vtoth/Library/Developer/Xamarin/android-sdk-mac_x86    Supported
    Android versions:
          2.1   (API level 7)
          2.2   (API level 8)
          2.3   (API level 10)
          3.1   (API level 12)
          4.0   (API level 14)
          4.0.3 (API level 15)
          4.3   (API level 18)
          4.4   (API level 19) Java SDK: /usr java version "1.6.0_65" Java(TM) SE Runtime Environment (build 1.6.0_65-b14-462-11M4609) Java
    HotSpot(TM) 64-Bit Server VM (build 20.65-b04-462, mixed mode)</p>
    
    <p>=== Build Information ===</p>
    
    <p>Release ID: 402040035 Git revision:
    1173cb1c45bc56cb702e82cd21a7c9d0cea4acbf Build date: 2014-04-17
    13:45:52-04 Xamarin addins: 53bde0041263928e8bd64686f5ca5a8e4338dd76</p>
    
    <p>=== Operating System ===</p>
    
    <p>Mac OS X 10.9.2</p>
  </blockquote>