Closes #27935: returned numeric value for 'FATAL' logging level.

Lib/logging/__init__.py

@@ -108,6 +108,7 @@ _levelToName = {
 }
 _nameToLevel = {
     'CRITICAL': CRITICAL,
+    'FATAL': FATAL,
     'ERROR': ERROR,
     'WARN': WARNING,
     'WARNING': WARNING,

Lib/test/test_logging.py

@@ -309,6 +309,10 @@ class BuiltinLevelsTest(BaseTest):
         self.assertEqual(logging.getLevelName('INFO'), logging.INFO)
         self.assertEqual(logging.getLevelName(logging.INFO), 'INFO')
 
+    def test_issue27935(self):
+        fatal = logging.getLevelName('FATAL')
+        self.assertEqual(fatal, logging.FATAL)
+
 class BasicFilterTest(BaseTest):
 
     """Test the bundled Filter class."""