Don't import Microsoft.Common.props if it has been imported already

[kzu]

Fixes #50573

[Copilot]

Pull Request Overview

This PR fixes issue #50573 by preventing duplicate imports of Microsoft.Common.props. The change adds a condition to check if Microsoft.Common.props has already been imported before attempting to import it again.

• Adds a check for the MicrosoftCommonPropsHasBeenImported property to prevent duplicate imports

[github-actions]

This PR is targeting main, which is now for .NET 11-facing work. If you intended to target .NET 10, either retarget this PR to release/10.0.1xx or make sure you backport the change to release/10.0.1xx after merging. See #50394 for more details.

[dsplaisted]

With this change, UseArtifactsOutput wouldn't work if Microsoft.Common.props was imported before Microsoft.NET.Sdk's Sdk.props. This is because before it imports the common props it sets the following:

<CustomAfterDirectoryBuildProps>$(CustomAfterDirectoryBuildProps);$(MSBuildThisFileDirectory)UseArtifactsOutputPath.props</CustomAfterDirectoryBuildProps>

I'm not sure if there's a good solution.

[marcpopMSFT]

Triage: @kzu not sure how to make this work. Why do you have to import common.props in your sdk?

[kzu]

@marcpopMSFT https://github.com/devlooped/SmallSharp/blob/main/src/SmallSharp/Sdk.props#L14C1-L15C1

In my case, I want to access MSBuildProjectExtensionsPath, for example. But besides my specific use case, this is the uniform pattern in all other targets, so for the sake of consistency, it would be important to implement it.