dotnet integration pack test IL issue

[erdembayar]

Please run any dotnet integration test like one below.

https://github.com/NuGet/NuGet.Client/blob/dev-eryondon-9949PackNoWarn/test/NuGet.Core.FuncTests/Dotnet.Integration.Test/PackCommandTests.cs#L5716-L5783

In the 1st run everything works as expected, but 2nd/3rd of same test fails with obscure error.

dotnet.exe pack -o C:\NuGetProj\NuGet.Client\.test\work\d7b832e8\913de640\ClassLibrary1 command failed with following log information :
 Microsoft (R) Build Engine version 16.9.0+57a23d249 for .NET
Copyright (C) Microsoft Corporation. All rights reserved.
  Determining projects to restore...
  All projects are up-to-date for restore.
  You are using a preview version of .NET. See: https://aka.ms/dotnet-core-preview
  ClassLibrary1 -> C:\NuGetProj\NuGet.Client\.test\work\d7b832e8\913de640\ClassLibrary1\bin\Debug\net5.0\ClassLibrary1.dll
C:\NuGetProj\NuGet.Client\.test\work\e9383fde\fd462388\sdk\5.0.200-servicing.21120.4\Sdks\NuGet.Build.Tasks.Pack\build\NuGet.Build.Tasks.Pack.targets(278,15): error MSB4064: The "Readme" parameter is not supported by the "PackTask" task. Verify the parameter exists on the task, and it is a settable public instance property. [C:\NuGetProj\NuGet.Client\.test\work\d7b832e8\913de640\ClassLibrary1\ClassLibrary1.csproj]
C:\NuGetProj\NuGet.Client\.test\work\e9383fde\fd462388\sdk\5.0.200-servicing.21120.4\Sdks\NuGet.Build.Tasks.Pack\build\NuGet.Build.Tasks.Pack.targets(221,5): error MSB4063: The "PackTask" task could not be initialized with its input parameters.  [C:\NuGetProj\NuGet.Client\.test\work\d7b832e8\913de640\ClassLibrary1\ClassLibrary1.csproj]

 Expected: True
Actual:   False

Workaround: Backup "NuGet.Client\artifacts\NuGet.Build.Tasks.Pack\bin\Debug\netstandard2.0\ilmerge\NuGet.Build.Tasks.Pack.dll" file somewhere then restore after each test run. Somehow this file get removed after each test run.

[nkolev92]

Fixed in NuGet/NuGet.Client#4488.

Not sure why it wasn't closed.