crash on 8.2 and cvshead - failed to add item to the left sibling

[
Sorry if this is a duplicate -- resending since it hasn't made it to the 
list after 1 1/2 hour, possibly due to large attachment (?); here's a 
URL instead:
http://www.joeconway.com/das_data_load_failure2.sql.gz
]

We just came upon a crash bug in Postgres >= 8.2. The attached
standalone script (just needs a database with plpgsql installed)
reproduces the crash for me on 32-bit machines (i686) but NOT on 64 bit
machines (x86_64), for Postgres 8.2 and cvs-head, but not on 8.1. We've
verified this on about four 32 bit machines, and four 64 bit machines
(including one each under vmware on the same host). All machines were
some flavor of Red Hat, Fedora, or Gentoo.

Here is the error:
8<--------------------------------------------------------------
das=# \i /home/jconway/pgsql/das_data_load_failure2.sql

[...snip...]
  das_tbl_das_status_log
------------------------

(1 row)

psql:/home/jconway/pgsql/das_data_load_failure2.sql:419: PANIC:  failed
to add item to the left sibling for "pk_status_log_2007_01_4_10"
CONTEXT:  COPY das_status_log_2007_01_4_10, line 27: "10
2007-Jan-25 03:06:59.372266 -0800       r_x_data
406,386,482,342,338,338,330,310,322,330,314,326,334,31..."
psql:/home/jconway/pgsql/das_data_load_failure2.sql:420: server closed
the connection unexpectedly         This probably means the server terminated abnormally         before or while
processingthe request.
 
psql:/home/jconway/pgsql/das_data_load_failure2.sql:420: connection to
server was lost
8<--------------------------------------------------------------

Here is a backtrace:
8<--------------------------------------------------------------
#0  0x00d2f402 in __kernel_vsyscall ()
#1  0x42901d40 in raise () from /lib/libc.so.6
#2  0x42903591 in abort () from /lib/libc.so.6
#3  0x082ed82e in errfinish (dummy=0) at elog.c:449
#4  0x082ee729 in elog_finish (elevel=22, fmt=0x832c0c4 "failed to add
item to the %s for \"%s\"") at elog.c:937
#5  0x080b0483 in _bt_pgaddtup (rel=0xb5b4302c, page=0x86c6bfc "",
itemsize=48, itup=0xb5e49d14, itup_off=36,     where=0x832b826 "left sibling") at nbtinsert.c:1654
#6  0x080ae849 in _bt_split (rel=0xb5b4302c, buf=252, firstright=40,
newitemoff=40, newitemsz=1312,     newitem=0x8680714, newitemonleft=0 '\0') at nbtinsert.c:843
#7  0x080ad965 in _bt_insertonpg (rel=0xb5b4302c, buf=252,
stack=0x869c3b4, keysz=4, scankey=0x8681538,     itup=0x8680714, afteritem=0, split_only_page=0 '\0') at 
nbtinsert.c:538
#8  0x080acd08 in _bt_doinsert (rel=0xb5b4302c, itup=0x8680714,
index_is_unique=1 '\001', heapRel=0xb5b42c7c)     at nbtinsert.c:141
#9  0x080b484a in btinsert (fcinfo=0xbfc80380) at nbtree.c:224
#10 0x082f393c in FunctionCall6 (flinfo=0x866ef9c, arg1=3048484908,
arg2=3217557044, arg3=3217557012, arg4=141339656,     arg5=3048483964, arg6=1) at fmgr.c:1267
#11 0x080ab427 in index_insert (indexRelation=0xb5b4302c,
values=0xbfc80634, isnull=0xbfc80614 "",     heap_t_ctid=0x86cac08, heapRelation=0xb5b42c7c, check_uniqueness=1
'\001') at indexam.c:196
#12 0x081a08e5 in ExecInsertIndexTuples (slot=0x86899e4,
tupleid=0x86cac08, estate=0x862cc14, is_vacuum=0 '\0')     at execUtils.c:1088
#13 0x0814fcd9 in CopyFrom (cstate=0x863a590) at copy.c:2082
#14 0x0814d90b in DoCopy (stmt=0x860bd14) at copy.c:1141
#15 0x082555a7 in ProcessUtility (parsetree=0x860bd14, params=0x0,
dest=0x860bbe4, completionTag=0xbfc80d1e "")     at utility.c:635
#16 0x08253bff in PortalRunUtility (portal=0x862ec1c, query=0x860bd70,
dest=0x860bbe4, completionTag=0xbfc80d1e "")     at pquery.c:1063
#17 0x08253d72 in PortalRunMulti (portal=0x862ec1c, dest=0x860bbe4,
altdest=0x860bbe4, completionTag=0xbfc80d1e "")     at pquery.c:1131
#18 0x08253482 in PortalRun (portal=0x862ec1c, count=2147483647,
dest=0x860bbe4, altdest=0x860bbe4,     completionTag=0xbfc80d1e "") at pquery.c:700
#19 0x0824deb2 in exec_simple_query (query_string=0x860b9cc "copy
das_status_log_2007_01_4_10 from stdin;")     at postgres.c:939
#20 0x08251b5e in PostgresMain (argc=4, argv=0x85b1c80,
username=0x85b1c50 "postgres") at postgres.c:3424
8<--------------------------------------------------------------

Joe