Building on a clean machine fails because ref assemblies are not installed

[KirillOsenkov]

wpf tmp fails to build with:

Microsoft.Common.CurrentVersion.targets(1259,5): error MSB3644: The reference assemblies for .NETFramework,Version=v4.7.2 were not found. To resolve this, install the Developer Pack (SDK/Targeting Pack) for this framework version or retarget your application. You can download .NET Framework Developer Packs at https://aka.ms/msbuild/developerpacks [C:\il-repack\ILRepack.IntegrationTests\Scenarios\WPFSampleApplication\WPFSampleApplication_yc2sehw3_wpftmp.csproj]