Clarify comments

Author: neonene

Lib/test/datetimetester.py

@@ -7297,9 +7297,10 @@ def test_update_type_cache(self):
 
     @unittest.skipIf(_interpreters is None, "missing _interpreters module")
     def test_static_type_concurrent_init_fini(self):
-        # gh-136421: When a managed static extension type is concurrently
-        # used by multiple interpreters, there was a crash due to misjudging
-        # its first initialization stage or last finalization one.
+        # gh-136421: When a managed static extension type is concurrently used
+        # by multiple interpreters, there was a crash due to the runtime state
+        # rather than an interpreter state being updated wrongly by misjudging
+        # the type's first initialization stage or last finalization one.
         script = textwrap.dedent("""
             import threading
             import _interpreters

Modules/_datetimemodule.c

@@ -7570,8 +7570,8 @@ PyMODINIT_FUNC
 PyInit__datetime(void)
 {
     PyInterpreterState *interp = _PyInterpreterState_GET();
-    // gh-136421: Ensure static types are fully finalized at the shutdown of
-    // the main interpreter rather than subinterpreters for concurrency.
+    // gh-136421: Ensure static types' runtime state gets cleared in shutting
+    // down the main interpreter rather than subinterpreters for concurrency.
     assert(interp != NULL && _Py_IsMainInterpreter(interp));
     if (init_static_types(interp, 0) < 0) {
         return NULL;