Need global.json to set the desired SDK version #5015

I have .NET Core 2.0.2-vspre-006949 installed as well as 2.0.0. When I try to build with Start-PSBuild, I get this error:

WARNING: The currently installed .NET Command Line Tools is not the required version.

Installed version: 2.0.2-vspre-006949
Required version: 2.0.0

Fix steps:

1. Remove the installed version from:
    - on windows '$env:LOCALAPPDATA\Microsoft\dotnet'
    - on macOS and linux '$env:HOME/.dotnet'
2. Run Start-PSBootstrap or Install-Dotnet
3. Start-PSBuild -Clean

FWIW I had just recently run Start-PSBootstrap and restarted the console. And when I got the above error I was running Start-PSBuild -Clean.

But in this case, the issue is easily fixed by putting a global.json file in the root of the repo with these contents:

{
  "sdk": {
    "version": "2.0.0"
  }
}

Environment data

I'm building on Windows PowerShell 5.1 on Windows 10 CU.

> $PSVersionTable

Name                           Value
----                           -----
PSVersion                      5.1.15063.608
PSEdition                      Desktop
PSCompatibleVersions           {1.0, 2.0, 3.0, 4.0...}
BuildVersion                   10.0.15063.608
CLRVersion                     4.0.30319.42000
WSManStackVersion              3.0
PSRemotingProtocolVersion      2.3
SerializationVersion           1.1.0.1