Issue #21742: Set stream to None after closing.
diff --git a/Lib/logging/handlers.py b/Lib/logging/handlers.py
index 30ad036..b7bf931 100644
--- a/Lib/logging/handlers.py
+++ b/Lib/logging/handlers.py
@@ -423,6 +423,7 @@
                 # we have an open file handle, clean it up
                 self.stream.flush()
                 self.stream.close()
+                self.stream = None  # See Issue #21742: _open () might fail.
                 # open a new file handle and get new stat info from that fd
                 self.stream = self._open()
                 self._statstream()