StreamLogWriter: Provide (no-op) close method. (#10884)

Some contexts try to close their reference to the stderr stream at logging shutdown, this ensures these don't break.

* Make pylint happy

An explicit `pass` is better here, but the docstring _is_ a statement.

Co-authored-by: Ash Berlin-Taylor <ash_github@firemirror.com>

airflow/utils/log/logging_mixin.py

@@ -93,6 +93,13 @@ class StreamLogWriter:
         self.level = level
         self._buffer = ''
 
+    def close(self):
+        """
+        Provide close method, for compatibility with the io.IOBase interface.
+
+        This is a no-op method.
+        """
+
     @property
     def closed(self):   # noqa: D402
         """

tests/utils/test_logging_mixin.py

@@ -96,3 +96,10 @@ class TestStreamLogWriter(unittest.TestCase):
 
         log = StreamLogWriter(logger, 1)
         self.assertIsNone(log.encoding)
+
+    def test_iobase_compatibility(self):
+        log = StreamLogWriter(None, 1)
+
+        self.assertFalse(log.closed)
+        # has no specific effect
+        log.close()