Graph build with traversal projects packs each TargetFramework of multi-targeting projects

[AArnott]

Issue Description

A csproj with a TargetFrameworks property should only be packed in the build of the project that has no TargetFramework global property defined. Traversal projects honor this, unless -graph is specified at the command line. Then all target frameworks try to pack. When this happens concurrently, the build often fails with a timing break.

Steps to Reproduce

It's simple, really. Take a simple csproj:

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <TargetFrameworks>net9.0;net8.0</TargetFrameworks>
  </PropertyGroup>

</Project>

A traversal that points to it:

<Project Sdk="Microsoft.Build.Traversal">
  <ItemGroup>
    <ProjectReference Include="SomePackage\SomePackage.csproj" />
  </ItemGroup>
</Project>

And a global.json:

{
	"sdk": {
		"version": "9.0.300",
		"rollForward": "patch",
		"allowPrerelease": false
	},
	"msbuild-sdks": {
		"Microsoft.Build.Traversal": "4.1.82"
	}
}

Or use Repro.zip

Then run dotnet pack -graph -bl. You'll likely see the break. And if you don't, you can try again (after removing build artifacts), or just inspect the .binlog to see that too many GenerateNuspec targets ran.

Then try again with just dotnet pack (again, in a clean state) and it will work properly.

Expected Behavior

I expect dotnet build -graph to run the Pack target only on SomePackage.csproj top-level, no TargetFramework properties specified.

Actual Behavior

Timing break due to overbuild of the Pack target.

  SomePackage net9.0 failed with 1 error(s) (0.2s) → SomePackage\bin\Release\net9.0\SomePackage.dll
    C:\Program Files\dotnet\sdk\9.0.300\Sdks\NuGet.Build.Tasks.Pack\build\NuGet.Build.Tasks.Pack.targets(221,5): error : The process cannot access the file 'C:\temp\msbuildbugrepro\SomePackage\obj\Release\SomePackage.1.0.0.nuspec' because it is being used by another process.
  SomePackage net8.0 succeeded (0.4s) → SomePackage\bin\Release\net8.0\SomePackage.dll

Analysis

No response

Versions & Configurations

No response

[rainersigwald]

@jeffkl do you have any thoughts on where in the layers this might be going wrong?