• This issue is blocking
• This issue is causing unreasonable pain

See dotnet/runtime#47984 for context. Basically, Xharness sets up CLI payloads for execution and when two runs are submitted in parallel to do this, it can collide.

Some kind of file-based semaphore would be a simple solution, or perhaps even a means to do nothing if the target directory already exists (will need to be sure it matches, though)

@ilyas1974 this is small and directly affecting day-to-day runtime team stuff so I put it in FR, please remove if you disagree.