Flush std{in,out,err} before closing it. Fixes #1074011.

Will backport to 2.4 and 2.3.

Misc/NEWS

@@ -10,6 +10,9 @@ 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 
+  an ferror() call.
+
 - min() and max() now support key= arguments with the same meaning as in
   list.sort().
 

Python/sysmodule.c

@@ -927,6 +927,13 @@ settrace() -- set the global debug tracing function\n\
 )
 /* end of sys_doc */ ;
 
+static int
+_check_and_flush (FILE *stream)
+{
+  int prev_fail = ferror (stream);
+  return fflush (stream) || prev_fail ? EOF : 0;
+}
+
 PyObject *
 _PySys_Init(void)
 {
@@ -940,9 +947,9 @@ _PySys_Init(void)
 	m = Py_InitModule3("sys", sys_methods, sys_doc);
 	sysdict = PyModule_GetDict(m);
 
-	sysin = PyFile_FromFile(stdin, "<stdin>", "r", NULL);
-	sysout = PyFile_FromFile(stdout, "<stdout>", "w", NULL);
-	syserr = PyFile_FromFile(stderr, "<stderr>", "w", NULL);
+	sysin = PyFile_FromFile(stdin, "<stdin>", "r", _check_and_flush);
+	sysout = PyFile_FromFile(stdout, "<stdout>", "w", _check_and_flush);
+	syserr = PyFile_FromFile(stderr, "<stderr>", "w", _check_and_flush);
 	if (PyErr_Occurred())
 		return NULL;
 #ifdef MS_WINDOWS