bug#8429: 24.0.50; regression: `flush-lines' does not flush all it should

["Drew Adams" <drew.adams@oracle.com>]

emacs -Q
 
Load libraries cygwin-mount.el, setup-cygwin.el, to be able to use grep
on Windows.  The libraries are here:
http://www.emacswiki.org/emacs/ElispArea
 
cd to the Emacs Lisp source directory.
 
M-x grep RET grep -nH -e "#" *.el */*.el RET
 
The grep output shows all matches for `#'.
 
C-x C-q to make the grep buffer writable.
 
M-x flush-lines RET ###autoload RET
 
Only the first few lines containing `###autoload' are flushed.
Repeating `flush-lines' flushes a few more.  But all should be flushed
(assuming point is at bob).  Same thing if you do `C-x h' before M-x
flush-lines.
 
This is a regression wrt Emacs 23.3 and older releases.  But the
`flush-lines' code itself seems not to have changed since 23.3.
 

In GNU Emacs 24.0.50.1 (i386-mingw-nt5.1.2600)
 of 2011-04-04 on 3249CTO
Windowing system distributor `Microsoft Corp.', version 5.1.2600
configured using `configure --with-gcc (4.5) --no-opt --cflags
-Ic:/imagesupport/include'