Revert "gh-127586: properly restore blocked signals in resource_tracker.py (GH-127587)"

This reverts commit 46006a1.

Author: hugovk

Lib/multiprocessing/resource_tracker.py

@@ -155,14 +155,13 @@ def ensure_running(self):
                 # that can make the child die before it registers signal handlers
                 # for SIGINT and SIGTERM. The mask is unregistered after spawning
                 # the child.
-                prev_sigmask = None
                 try:
                     if _HAVE_SIGMASK:
-                        prev_sigmask = signal.pthread_sigmask(signal.SIG_BLOCK, _IGNORED_SIGNALS)
+                        signal.pthread_sigmask(signal.SIG_BLOCK, _IGNORED_SIGNALS)
                     pid = util.spawnv_passfds(exe, args, fds_to_pass)
                 finally:
-                    if prev_sigmask is not None:
-                        signal.pthread_sigmask(signal.SIG_SETMASK, prev_sigmask)
+                    if _HAVE_SIGMASK:
+                        signal.pthread_sigmask(signal.SIG_UNBLOCK, _IGNORED_SIGNALS)
             except:
                 os.close(w)
                 raise

Lib/test/_test_multiprocessing.py

@@ -6044,21 +6044,6 @@ def test_resource_tracker_exit_code(self):
                 self._test_resource_tracker_leak_resources(
                     cleanup=cleanup,
                 )
-    @unittest.skipUnless(hasattr(signal, "pthread_sigmask"), "pthread_sigmask is not available")
-    def test_resource_tracker_blocked_signals(self):
-        #
-        # gh-127586: Check that resource_tracker does not override blocked signals of caller.
-        #
-        from multiprocessing.resource_tracker import ResourceTracker
-        signals = {signal.SIGTERM, signal.SIGINT, signal.SIGUSR1}
-
-        for sig in signals:
-            signal.pthread_sigmask(signal.SIG_SETMASK, {sig})
-            self.assertEqual(signal.pthread_sigmask(signal.SIG_BLOCK, set()), {sig})
-            tracker = ResourceTracker()
-            tracker.ensure_running()
-            self.assertEqual(signal.pthread_sigmask(signal.SIG_BLOCK, set()), {sig})
-            tracker._stop()
 
 class TestSimpleQueue(unittest.TestCase):