bpo-45128: fixes test_multiprocessing_fork mysterious crash (GH-28387)

Author: sobolevn

Lib/test/test_logging.py

@@ -4437,8 +4437,10 @@ def _extract_logrecord_process_name(key, logMultiprocessing, conn=None):
             name = mp.current_process().name
 
             r1 = logging.makeLogRecord({'msg': f'msg1_{key}'})
-            del sys.modules['multiprocessing']
-            r2 = logging.makeLogRecord({'msg': f'msg2_{key}'})
+
+            # https://bugs.python.org/issue45128
+            with support.swap_item(sys.modules, 'multiprocessing', None):
+                r2 = logging.makeLogRecord({'msg': f'msg2_{key}'})
 
             results = {'processName'  : name,
                        'r1.processName': r1.processName,
@@ -4487,7 +4489,6 @@ def test_multiprocessing(self):
             if multiprocessing_imported:
                 import multiprocessing
 
-
     def test_optional(self):
         r = logging.makeLogRecord({})
         NOT_NONE = self.assertIsNotNone

Misc/NEWS.d/next/Tests/2021-09-16-17-22-35.bpo-45128.Jz6fl2.rst

@@ -0,0 +1,2 @@
+Fix ``test_multiprocessing_fork`` failure due to ``test_logging`` and
+``sys.modules`` manipulation.