CopyToOutputDirectory doesn't work if folder name contains @

[meum]

Describe the bug

If the project folder has @ in the name, files with <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory> doesn't get copied to the output directory. This works in 9.0.105, but is broken in 9.0.203.
This causes broken builds for us because Jenkins uses @2 in folder names when the same pipeline is running multiples times in parallel.

To Reproduce

#!/bin/bash

rm -rf consoleapp@2
dotnet new console -o consoleapp@2
cd consoleapp@2
dotnet new globaljson --sdk-version 9.0.203 --roll-forward disable
touch test.txt
cat > consoleapp@2.csproj <<EOF
<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>net9.0</TargetFramework>
    <ImplicitUsings>enable</ImplicitUsings>
    <Nullable>enable</Nullable>
  </PropertyGroup>

  <ItemGroup>
    <None Update="test.txt">
      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
    </None>
  </ItemGroup>
</Project>
EOF

dotnet build -v diag
ls bin/Debug/net9.0/test.txt

Fails with ls: cannot access 'bin/Debug/net9.0/test.txt': No such file or directory

[edvilme]

I think this is related to #11442