[llvm] [lit] Ensure ulimit does not persist across tests (PR #164485)

[Aiden Grossman via llvm-commits]

boomanaiden154 wrote:

> Good catch! I wonder if we should run tools like ruff over the lit files to catch other potential issues?

Maybe. I feel like getting a linter with a reasonable set of rules clean on a codebase like lit's is going to be a decent amount of work though.

https://github.com/llvm/llvm-project/pull/164485