[3.13] gh-138163: skip failures if tests are run with SCHED_BATCH on glibc (GH-138576) (GH-138819)

(cherry picked from commit 4929414)


This backport omits SCHED_DEADLINE, which was added in 3.14.

---------

Co-authored-by: jxes993409 <68891412+jxes993409@users.noreply.github.com>
Co-authored-by: Petr Viktorin <encukou@gmail.com>

Author: 3 people

Lib/test/test_posix.py

@@ -1991,6 +1991,11 @@ def test_setscheduler_only_param(self):
     @requires_sched
     @unittest.skipIf(sys.platform.startswith(('freebsd', 'netbsd')),
                      "bpo-34685: test can fail on BSD")
+    @unittest.skipIf(platform.libc_ver()[0] == 'glibc' and
+                     os.sched_getscheduler(0) in [
+                        os.SCHED_BATCH,
+                        os.SCHED_IDLE],
+                     "Skip test due to glibc posix_spawn policy")
     def test_setscheduler_with_policy(self):
         policy = os.sched_getscheduler(0)
         priority = os.sched_get_priority_min(policy)