Userlocal workload installation/updates are broken in 8.0.300

[baronfel]

          @Mr-MooMoo, I reproduced the issue. It is different from the one @anpin ran into with the 8.0.2xx SDK.

@marcpopMSFT @dsplaisted @baronfel it seems that userlocal is broken in the 8.0.3xx band.

The issue can be reproduced with these commands (on any linux-x64 distro).

mkdir /tmp/repro
cd /tmp/repro
mkdir dotnet
cd dotnet
wget https://download.visualstudio.microsoft.com/download/pr/86497c4f-3dc8-4ee7-9f6a-9e0464059427/293d074c28bbfd9410f4db8e021fa290/dotnet-sdk-8.0.301-linux-x64.tar.gz
tar xvf *.tar.gz
mkdir -p metadata/workloads/8.0.300
touch metadata/workloads/8.0.300/userlocal
chmod -R -w .
export DOTNET_ROOT=$(pwd)
export PATH=$(pwd):$PATH
cd ..
mkdir home
cd home
export HOME=$(pwd)
dotnet workload update

Originally posted by @tmds in #37706 (comment)

We should ensure that userlocal configurations work with workloads sets - all state and workload set packs should go to the userlocal location instead of the SDK location.

NOTE:
When I did the repro steps I had to make sure to change to a user without root permissions so that I couldn't accidentally modify the SDK install

[baronfel]

@tmds I'm assuming that this is broken in 9.0.100 previews as well, right? Since the work from 8.0.300 has flowed into main at this point?

[tmds]

@tmds I'm assuming that this is broken in 9.0.100 previews as well, right?

Yes, reported for .NET 9 in #41726.