Merge pull request #2669 from jakesays/master

Issue #2666 - MefHostServices fails loading unsigned assemblies

src/Workspaces/Core/Portable/Workspace/Host/Mef/MefHostServices.cs

@@ -135,6 +135,11 @@ private static Assembly TryLoadNearbyAssembly(string assemblySimpleName)
             var assemblyVersion = thisAssemblyName.Version;
             var publicKeyToken = thisAssemblyName.GetPublicKeyToken().Aggregate(string.Empty, (s, b) => s + b.ToString("x2"));
 
+            if (string.IsNullOrEmpty(publicKeyToken))
+            {
+                publicKeyToken = "null";
+            }
+
             var assemblyName = new AssemblyName(string.Format("{0}, Version={1}, Culture=neutral, PublicKeyToken={2}", assemblySimpleName, assemblyVersion, publicKeyToken));
 
             try