Change to flush and close logic to fix #1760556.

Lib/logging/__init__.py

@@ -728,6 +728,7 @@ def flush(self):
         """
         Flushes the stream.
         """
+        if self.stream:
             self.stream.flush()
 
     def emit(self, record):
@@ -778,9 +779,11 @@ def close(self):
         """
         Closes the stream.
         """
+        if self.stream:
             self.flush()
             self.stream.close()
             StreamHandler.close(self)
+            self.stream = None
 
     def _open(self):
         """