Investigate issue when NuGet updater pins a transitive dependency

[brettfo]

Scenario seen in an internal conversation.

A transitive dependency needed to be pinned to a specific version in project.csproj, but the repo was using Central Package Management and the corresponding entry in Directory.Packages.props was missing.

E.g., the following change was made in project.csproj

 ...
+<PackageReference Include="Some.Transitive.Dependency" />
 ...

However the following change was expected, but not made in `Directory.Packages.props

 ...
+<PackageVersion Include="Some.Transitive.Dependency" Version="1.2.3" />
 ...