write past chunk end in ExprContext / to_char

With today's CVS code (originally noticed with 8.2beta3), on a PC where
INT_MAX=0x7FFFFFFF=2147483647

postgres=# select version();
                                                             version                                                             
---------------------------------------------------------------------------------------------------------------------------------
 PostgreSQL 8.3devel on i386-unknown-netbsdelf4.99.20, compiled by GCC gcc (GCC) 4.1.2 20070110 prerelease (NetBSD nb1 20070603)
(1 row)

postgres=# select to_char(2147483647,'999,999,999');
   to_char    
--------------
  ###,###,###
(1 row)

postgres=# select to_char(2147483648,'999,999,999');
WARNING:  detected write past chunk end in ExprContext 0x845509c
WARNING:  detected write past chunk end in ExprContext 0x845509c
   to_char    
--------------
  ###,###,###
(1 row)

postgres=# select to_char(2147483648,'99,999,999');
   to_char   
-------------
  ##,###,###
(1 row)

postgres=# select to_char(2147483648,'9,999,999,999');
    to_char     
----------------
  2,147,483,648
(1 row)

postgres=# select to_char(1234567890123,'999,999,999,999');
WARNING:  detected write past chunk end in ExprContext 0x845509c
WARNING:  detected write past chunk end in ExprContext 0x845509c
     to_char      
------------------
  ###,###,###,###
(1 row)

postgres=# select to_char(1234567890123,'99,999,999,999');
     to_char     
-----------------
  ##,###,###,###
(1 row)

So strangely, to get the worrying WARNING, I seem to need >INT_MAX with
a format string with 1 less positions than necessary - no wonder I
seemed to only see it randomly...

Thoughts?

Cheers,

Patrick