#9184: fix default value for "buffering" param of open().

Doc/library/functions.rst

@@ -676,7 +676,7 @@ are always available.  They are listed here in alphabetical order.
    :meth:`__index__` method that returns an integer.
 
 
-.. function:: open(file, mode='r', buffering=None, encoding=None, errors=None, newline=None, closefd=True)
+.. function:: open(file, mode='r', buffering=-1, encoding=None, errors=None, newline=None, closefd=True)
 
    Open *file* and return a corresponding stream.  If the file cannot be opened,
    an :exc:`IOError` is raised.

Modules/_io/_iomodule.c

@@ -176,7 +176,7 @@ PyObject *PyExc_BlockingIOError = (PyObject *)&_PyExc_BlockingIOError;
  * The main open() function
  */
 PyDoc_STRVAR(open_doc,
-"open(file, mode='r', buffering=None, encoding=None,\n"
+"open(file, mode='r', buffering=-1, encoding=None,\n"
 "     errors=None, newline=None, closefd=True) -> file object\n"
 "\n"
 "Open file and return a stream.  Raise IOError upon failure.\n"