user's preferences deleted when out of diskspace

I've found a bug in squirrelmail 1.4.2 :-(

If a system is out of disk space the users preference
file get
truncated.

The check in functions/file_prefs.php doesn't fail is a
system is out of diskspace:

if ( @fwrite($file, $Key . '=' . $Value . "\n") ===
FALSE ) {

If no data is written fwrite returns (int) 0 and isn't
(boolean) FALSE if "===" is used and the zero sized
.tmp gets copied over the user's preference file.

see:

http://sourceforge.net/mailarchive/forum.php?thread_id=4034978&forum_id=7139