test.test_concurrent_futures.test_deadlock test_pyrepl failed on 1-core-VM

Bug report

Bug description:

While working on reproducible builds for openSUSE (sponsored by the NLnet NGI0 fund), I found that our python313 package fails to build on 1-core-VMs from two failing tests.

Full build log: https://rb.zq1.de/other/python313/build-j1.log

2 re-run tests:
    test.test_concurrent_futures.test_deadlock test_pyrepl

2 tests failed:
    test.test_concurrent_futures.test_deadlock test_pyrepl

447 tests OK.

Total duration: 3 hour 35 sec
Total tests: run=42,874 (filtered) failures=7 skipped=1,745
Total test files: run=466/468 (filtered) failed=2 skipped=15 resource_denied=4 rerun=2

If those tests cannot pass in such an env, they should be skipped automatically.

CPython versions tested on:

3.13

Operating systems tested on:

Linux

Start by reviewing the linked build log and reproducing test.test_concurrent_futures.test_deadlock and test_pyrepl on a one-core Linux VM. Determine whether the failures are specific to single-core environments, then make the affected tests skip automatically there; done means the tests no longer fail in that environment while the broader test run remains valid.