Partially revert #1074011; don't try to fflush stdin.

Backported to 2.3 and 2.4.

Misc/NEWS

@@ -10,7 +10,7 @@ What's New in Python 2.5 alpha 1?
 Core and builtins
 -----------------
 
-- Bug #1074011: closing sys.std{in,out,err} now causes a flush() and 
+- Bug #1074011: closing sys.std{out,err} now causes a flush() and 
   an ferror() call.
 
 - min() and max() now support key= arguments with the same meaning as in

Python/sysmodule.c

@@ -947,7 +947,16 @@ _PySys_Init(void)
 	m = Py_InitModule3("sys", sys_methods, sys_doc);
 	sysdict = PyModule_GetDict(m);
 
-	sysin = PyFile_FromFile(stdin, "<stdin>", "r", _check_and_flush);
+	/* Closing the standard FILE* if sys.std* goes aways causes problems
+	 * for embedded Python usages. Closing them when somebody explicitly
+	 * invokes .close() might be possible, but the FAQ promises they get
+	 * never closed. However, we still need to get write errors when
+	 * writing fails (e.g. because stdout is redirected), so we flush the
+	 * streams and check for errors before the file objects are deleted.
+	 * On OS X, fflush()ing stdin causes an error, so we exempt stdin
+	 * from that procedure.
+	 */
+	sysin = PyFile_FromFile(stdin, "<stdin>", "r", NULL);
 	sysout = PyFile_FromFile(stdout, "<stdout>", "w", _check_and_flush);
 	syserr = PyFile_FromFile(stderr, "<stderr>", "w", _check_and_flush);
 	if (PyErr_Occurred())