OK, I lied. On Windows, _IOLBF seems to be the same as full
buffering, so to get the normal behavior back, I set it to
unbuffered.
diff --git a/Modules/main.c b/Modules/main.c
index 3057e46..23a910e 100644
--- a/Modules/main.c
+++ b/Modules/main.c
@@ -204,10 +204,14 @@
#endif
}
else if (Py_InteractiveFlag) {
- char *ibuffer = malloc(BUFSIZ);
- char *obuffer = malloc(BUFSIZ);
- setvbuf(stdin, ibuffer, _IOLBF, BUFSIZ);
- setvbuf(stdout, obuffer, _IOLBF, BUFSIZ);
+#ifdef MS_WINDOWS
+ /* Doesn't have to have line-buffered -- use unbuffered */
+ setvbuf(stdin, (char *)NULL, _IONBF, BUFSIZ);
+ setvbuf(stdout, (char *)NULL, _IONBF, BUFSIZ);
+#else
+ setvbuf(stdin, (char *)NULL, _IOLBF, BUFSIZ);
+ setvbuf(stdout, (char *)NULL, _IOLBF, BUFSIZ);
+#endif
/* Leave stderr alone - it should be unbuffered anyway. */
}