pythongh-90102: Fix pyio _isatty_open_only() (python#125089)

cmaloney · efimov-mikhail · commit 148e3fe6443a · 2024-10-09T13:08:26.000+03:00
Spotted by @ngnpope. `isatty` returns False to indicate the file is not a TTY. The C implementation of _io does that (`Py_RETURN_FALSE`) but I got the bool backwards in the _pyio implementaiton.
diff --git a/Lib/_pyio.py b/Lib/_pyio.py
@@ -1806,7 +1806,7 @@ def _isatty_open_only(self):
         """
         if (self._stat_atopen is not None
             and not stat.S_ISCHR(self._stat_atopen.st_mode)):
-            return True
+            return False
         return os.isatty(self._fd)
 
     @property
