sdk: Native DLL not found with dotnet cli win-x64 while testing with xunit targeting net451

Steps to reproduce

project.json:

{
  "version": "1.0.0-*",
  "buildOptions": {
    "emitEntryPoint": true
  },
  "dependencies": {
    "xunit": "2.1.0-*",
    "dotnet-test-xunit": {
      "version": "1.0.0-rc2-*",
      "target": "package"
    },
    "Microsoft.NETCore.Platforms": "1.0.1-rc2-*"
  },
  "frameworks": {
    "net451": {
    }
  },
  "testRunner": "xunit"
}

Program.cs:

using System;

namespace ConsoleApplication
{
    public class Program
    {
        public static void Main(string[] args)
        {
            Console.WriteLine("Hello World!");
        }
    }
}

Commands:

dotnet restore
dotnet test

Expected behavior

Working test run, as with .NET Core 1.0 RC2:

xUnit.net .NET CLI test runner (64-bit win10-x64)
  Discovering: test-xunit
  Discovered:  test-xunit
=== TEST EXECUTION SUMMARY ===
   test-xunit.dll  Total: 0
SUMMARY: Total: 1 targets, Passed: 1, Failed: 0.

Actual behavior

xUnit.net .NET CLI test runner (32-bit win10-x86)
System.DllNotFoundException: Die DLL "Microsoft.DiaSymReader.Native.x86.dll": Das angegebene Modul wurde nicht gefunden. (Ausnahme von HRESULT: 0x8007007E) kann nicht geladen werden.
SUMMARY: Total: 1 targets, Passed: 0, Failed: 1.

The error message says, that the file Microsoft.DiaSymReader.Native.x86.dll could not be found.

The full build output is stored in .\Debug\net451\win7-x64, which only contains a Microsoft.DiaSymReader.Native.amd64.dll.

When I specify an explicit -r win7-x86, the output gets stored in .\Debug\net451\win7-x86, but - according to the Process Monitor - gets searched for in the .\Debug\net451\win7-x64 folder.

Using the x86 version of dotnet-cli works as expected for both net451 and netcoreapp1.0.

Environment data

dotnet --info output:

.NET Command Line Tools (1.0.0-preview1-002702)

Product Information:
 Version:     1.0.0-preview1-002702
 Commit Sha:  6cde21225e

Runtime Environment:
 OS Name:     Windows
 OS Version:  10.0.10586
 OS Platform: Windows
 RID:         win10-x64