Installing the 6.0.2 ref pack MSI removes the 6.0.0 ref pack MSI

Description

The 6.0.2 ref pack installer uninstalls the 6.0.0 ref pack, even when the 6.0.100 SDK is still installed.

Reproduction Steps

1. Install the .NET SDK v6.0.100 through VS (so it won’t be fully uninstalled by the 6.0.102 installer)
2. Install the .NET SDK v6.0.102 through the exe installer
3. See that there is no packs/Microsoft.NETCore.App.Ref/6.0.0 folder, but there is a packs/Microsoft.NETCore.App.Ref/6.0.2 folder.

Expected behavior

The 6.0.0 ref pack should be available on disk whenever the 6.0.100 SDK is installed.

Actual behavior

The 6.0.102 installer removes the 6.0.0 ref pack and replaces it with the 6.0.2 ref pack even though the 6.0.100 SDK is still installed.

Regression?

Shipping new versioned ref packs with the SDK is a new experience in 6.x, so this is probably not a regression.

Known Workarounds

Install the 6.0.100 sdk through the exe installer after 6.0.102 is installed

Configuration

Windows x64

Other information

cc: @AndyAyersMS, who initially discovered this issue.

cc: @NikolaMilosavljevic

[jkoritzinsky]

@AndyAyersMS was the person who had the repro. I just had more context about the likely underlying bug, so he had me make the issue.

[AraHaan]

One option is to start by building the local ref pack first, then compile the things that depend on it after that.