为什么64位MSBuild要加载32位扩展?

使用以下MSBuild项目文件:

<Project xmlns="http://schemas.microsoft.com/developer/msbuild/2003" ToolsVersion="4.0">
    <Target Name="test">
        <Message Text="bin path: $(MSBuildBinPath)" />
        <Message Text="extensions path: $(MSBuildExtensionsPath)" />
        <Message Text="extensions path (x86): $(MSBuildExtensionsPath32)" />
        <Message Text="extensions path (x64): $(MSBuildExtensionsPath64)" />
    </Target>
</Project>

Microsoft (R) Build Engine Version 4.0.30319.1
[Microsoft .NET Framework, Version 4.0.30319.1]
Copyright (C) Microsoft Corporation 2007. All rights reserved.

Build started 8/27/2010 9:56:35 AM.
Project "D:\5\test.proj" on node 1 (default targets).
test:
  bin path: C:\Windows\Microsoft.NET\Framework64\v4.0.30319
  extensions path: C:\Program Files (x86)\MSBuild
  extensions path (x86): C:\Program Files (x86)\MSBuild
  extensions path (x64): C:\Program Files\MSBuild
Done Building Project "D:\5\test.proj" (default targets).


Build succeeded.
    0 Warning(s)
    0 Error(s)

Time Elapsed 00:00:00.03

MSBuild显然知道32位和64位扩展路径,从二进制路径看来,我运行的是64位扩展路径MSBuild.exe文件,但出于某种原因,它认为应该从 Program Files (x86) 而不是 Program Files . 这给我带来了麻烦,因为我有一个需要加载的扩展,必须在32位/64位进程中正确加载,而且它不会加载(MSBuild正在尝试在64位进程中加载32位版本)。