Noted by Guido:

freddrake · freddrake · commit 43b89b637f98 · 2000-04-05T15:00:38.000Z
Note in the "Caveats" section should refer to the exit() function, not
exit_thread().
diff --git a/Doc/lib/libthread.tex b/Doc/lib/libthread.tex
@@ -108,7 +108,7 @@ \section{\module{thread} ---
 
 \item
 Calling \function{sys.exit()} or raising the \exception{SystemExit}
-exception is equivalent to calling \function{exit_thread()}.
+exception is equivalent to calling \function{exit()}.
 
 \item
 Not all built-in functions that may block waiting for I/O allow other
