Of course, you meant "#if 0" and not "#ifdef 0". :)

gvanrossum · gvanrossum · commit 367e46a9432c · 2000-08-01T18:28:44.000Z
diff --git a/Include/pyport.h b/Include/pyport.h
@@ -281,7 +281,7 @@ extern double hypot(double, double);
 /* If the fd manipulation macros aren't defined,
    here is a set that should do the job */
 
-#ifdef 0 /* disabled and probably obsolete */
+#if 0 /* disabled and probably obsolete */
 
 #ifndef	FD_SETSIZE
 #define	FD_SETSIZE	256
