Set 'visualbell' in test 72 to avoid a beep.

runtime/doc/todo.txt

@@ -36,8 +36,6 @@ Before release 7.3:
 Better Czech keymap. (Stepnem, 2010 May 4)  Use if no response from Jiri
 Tobisek.
 
-test72 causes a beep for using "u" when it doesn't work.
-
 :!cmd completion doesn't work on Windows. (Yue Wu).
 Problem with space in path?
 

src/testdir/test72.in

@@ -6,7 +6,7 @@ STARTTEST
 :so small.vim
 :"
 :" Test 'undofile': first a simple one-line change.
-:set nocompatible viminfo+=nviminfo
+:set nocompatible viminfo+=nviminfo visualbell
 :set ul=100 undofile nomore
 :e! Xtestfile
 ggdGithis is one line:set ul=100