Pathmap does not seem to be working, resulting in determinism failure

Version Used: .NET SDK 5.0.101

For simplicity the repro doesn’t reference an NuGet package that includes .cs files out of the package cache, but /pathmap appears to not be working for .cs files out of the package cache either. I can provide a repro involving the package cache if that is useful.

Repro.csproj

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <TargetFramework>net5.0</TargetFramework>
    <IncludeSymbols>true</IncludeSymbols>
    <ContinuousIntegrationBuild>true</ContinuousIntegrationBuild>
  </PropertyGroup>

</Project>

Class1.cs

public class Class1 { }

dotnet pack -c Release creates a package that does this:

Here’s what the SDK provided to csc:

Here are the filenames in the PDB (in the case of the repro that includes source from the package cache, the package cache path is not mapped either):

[tmat]

https://github.com/NuGet/Home/issues/9810

[jnm2]

The 5.0.302 SDK seems to have switched to using commas instead of semicolons in the pathmap. This bug was fixed somewhere between 5.0.101 and 5.0.302.