Scheduler tests fail on DragonFly BSD

[serhiy-storchaka]

Bug report

5 tests in test_os.test_posix fail on DragonFly BSD, because the scheduler API requires privileges there, even for the calling process:

ERROR: test_get_and_set_scheduler_and_param (test.test_os.test_posix.PosixTester)
    mine = posix.sched_getscheduler(0)
PermissionError: [Errno 1] Operation not permitted

The tests are already skipped when the API is present but does not work, but only for ENOSYS, added in gh-78831 for musl:

    try:
        posix.sched_getscheduler(0)
    except OSError as e:
        if e.errno == errno.ENOSYS:
            return False
    return True

EPERM should be handled the same way. Note that other errors are silently ignored here and the API is reported as supported.

test_sched_rr_get_interval fails likewise, and it is the only scheduler test which is not decorated with @requires_sched.

Linked PRs

• gh-154441: Skip the scheduler tests if the API requires privileges #154442
• [3.15] gh-154441: Skip the scheduler tests if the API requires privileges (GH-154442) #154447
• [3.14] gh-154441: Skip the scheduler tests if the API requires privileges (GH-154442) #154448
• [3.13] gh-154441: Skip the scheduler tests if the API requires privileges (GH-154442) #154449