Incorrect implementation of `truncate` in `test_free_threading` for IO

[picnixz]

Bug report

Bug description:

        def truncate(barrier, b, *ignore):
            barrier.wait()
            try: b.truncate(0)
            except: BufferError  # ignore exported buffer

should be

        def truncate(barrier, b, *ignore):
            barrier.wait()
            try: b.truncate(0)
            except BufferError: pass  # ignore exported buffer

instead.

CPython versions tested on:

CPython main branch

Operating systems tested on:

No response

Linked PRs

• gh-138360: Fix test_free_threading for IO objects #138359

[picnixz]

I suggested including this fix into the backport directly instead of having a new PR again for 3.14 only.