fix typo, refs #21677

tests/test_backup.py

@@ -71,7 +71,7 @@ def check_local_backup(path):
     for d in os.listdir(path):
         subd = os.path.join(path, d)
         latest = os.path.join(subd, 'latest')
-        if os.exists(latest):
+        if os.path.exists(latest):
             mtime = os.path.getmtime(latest)
             d = datetime.fromtimestamp(mtime)
             now = datetime.now()