Linux x64 release SourceBuild build break in CI

[jkotas]

Build Linux x64 release SourceBuild failed in #67466 with:

2022-04-01T23:55:41.3669226Z   /__w/1/s/.dotnet/sdk/6.0.100/Sdks/Microsoft.NET.Sdk/targets/Microsoft.PackageDependencyResolution.targets(267,5): error NETSDK1047: Assets file '/__w/1/s/artifacts/source-build/self/src/artifacts/obj/coreclr/crossgen2/project.assets.json' doesn't have a target for 'net6.0/centos.7-x64'. Ensure that restore has run and that you have included 'net6.0' in the TargetFrameworks for your project. You may also need to include 'centos.7-x64' in your project's RuntimeIdentifiers. [/__w/1/s/artifacts/source-build/self/src/src/coreclr/tools/aot/crossgen2/crossgen2.csproj]
2022-04-01T23:55:41.3672297Z       0 Warning(s)
2022-04-01T23:55:41.3673078Z       1 Error(s)
2022-04-01T23:55:41.3673750Z   

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Issue Details

---

Build Linux x64 release SourceBuild failed in #67466 with:

2022-04-01T23:55:41.3669226Z   /__w/1/s/.dotnet/sdk/6.0.100/Sdks/Microsoft.NET.Sdk/targets/Microsoft.PackageDependencyResolution.targets(267,5): error NETSDK1047: Assets file '/__w/1/s/artifacts/source-build/self/src/artifacts/obj/coreclr/crossgen2/project.assets.json' doesn't have a target for 'net6.0/centos.7-x64'. Ensure that restore has run and that you have included 'net6.0' in the TargetFrameworks for your project. You may also need to include 'centos.7-x64' in your project's RuntimeIdentifiers. [/__w/1/s/artifacts/source-build/self/src/src/coreclr/tools/aot/crossgen2/crossgen2.csproj]
2022-04-01T23:55:41.3672297Z       0 Warning(s)
2022-04-01T23:55:41.3673078Z       1 Error(s)
2022-04-01T23:55:41.3673750Z   

Author:	jkotas
Assignees:	-
Labels:	area-Infrastructure-coreclr, untriaged
Milestone:	-

[jkotas]

cc @agocke . This was likely introduced by #65948

[agocke]

:( Investigating...

[agocke]

This is rather strange actually. I've managed to repro the problem locally, but when I examine the listed project.assets.json file, there's an entry for net6.0/centos.7-x64.