Build fails due to missing RoslynTools.MSBuild 16.0.0-alpha

I wasn’t sure whether this issue belongs here or in dotnet/arcade. Please feel free to move it.

Steps to reproduce: Clone repository, run build.cmd.

Results:

dotnet-install: Downloading link: https://dotnetcli.azureedge.net/dotnet/Sdk/3.0.100-preview3-010436/dotnet-sdk-3.0.100-preview3-010436-win-x64.zip
dotnet-install: Extracting zip from https://dotnetcli.azureedge.net/dotnet/Sdk/3.0.100-preview3-010436/dotnet-sdk-3.0.100-preview3-010436-win-x64.zip
dotnet-install: Adding to current process PATH: "C:\Users\user\source\repos\winforms\.dotnet\". Note: This change will not be visible if PowerShell was run as a child process.
dotnet-install: Installation finished
Downloading vswhere
Downloading RoslynTools.MSBuild 16.0.0-alpha
No package matching package identifier RoslynTools.MSBuild and version 16.0.0-alpha was found in the given feed.

Version 16.0.0-alpha of the package indeed does not appear to exist, but 16.0.0-rc1-alpha does.

Additionally, running build a second time results in a different error:

Exception calling "Start" with "0" argument(s): "The system cannot find the file specified"
System.Management.Automation.MethodInvocationException: Exception calling "Start" with "0" argument(s): "The system cannot find the file specified" ---> System.ComponentModel.Win32Exception: The system cannot find the file specified
   at System.Diagnostics.Process.StartWithCreateProcess(ProcessStartInfo startInfo)
   at CallSite.Target(Closure , CallSite , Object )
   --- End of inner exception stack trace ---
   at System.Management.Automation.ExceptionHandlingOps.CheckActionPreference(FunctionContext funcContext, Exception exception)
   at System.Management.Automation.Interpreter.ActionCallInstruction`2.Run(InterpretedFrame frame)
   at System.Management.Automation.Interpreter.EnterTryCatchFinallyInstruction.Run(InterpretedFrame frame)
   at System.Management.Automation.Interpreter.EnterTryCatchFinallyInstruction.Run(InterpretedFrame frame)
at Exec-Process, C:\Users\user\source\repos\winforms\eng\common\tools.ps1: line 69
at MSBuild, C:\Users\user\source\repos\winforms\eng\common\tools.ps1: line 476
at InitializeToolset, C:\Users\user\source\repos\winforms\eng\common\tools.ps1: line 422
at Build, C:\Users\user\source\repos\winforms\eng\common\Build.ps1: line 76
at <ScriptBlock>, C:\Users\user\source\repos\winforms\eng\common\Build.ps1: line 125
at <ScriptBlock>, <No file>: line 1

[zsd4yr]

thanks @ArrowCase I am actively working on a workaround for us here but this is an underlying Arcade issue

[zsd4yr]

This should be solved by a workaround on our end as part of #647