#6787: reference fix.

Doc/library/thread.rst

@@ -156,7 +156,7 @@ In addition to these methods, lock objects can also be used via the
   module is available, interrupts always go to the main thread.)
 
 * Calling :func:`sys.exit` or raising the :exc:`SystemExit` exception is
-  equivalent to calling :func:`exit`.
+  equivalent to calling :func:`thread.exit`.
 
 * Not all built-in functions that may block waiting for I/O allow other threads
   to run.  (The most popular ones (:func:`time.sleep`, :meth:`file.read`,