New warning: `unused variable ‘st’ [-Wunused-variable]`

# Bug report

### Bug description:

Popped up in https://github.com/python/cpython/pull/117372/files and https://github.com/python/cpython/pull/117371/files

### CPython versions tested on:

CPython main branch

### Operating systems tested on:

_No response_