backend dies on 7.1.1 loading large datamodel.

I just checked out CVS this morning the REL7_1_STABLE branch. I
configured it with:

./configure --enable-debug

and ran the regression test fine on OpenBSD 2.8 (AMD processor) (The
same problem has been reproduced by someone else on RH6.2)

I then proceed to load the OpenACS datamodel and had the backend crash.
This datamodel loads fine on 7.1.

I can send the datamodel and core file if needed. I loaded GDB with the
core file and got the following:

$ gdb /usr/local/pgsql/bin/postmaster postgres.core
GNU gdb 4.16.1
:: snip ::
Program terminated with signal 11, Segmentation fault.
:: snip ::
#0 SPI_gettypeid (tupdesc=0x0, fnumber=1) at spi.c:501
501 if (tupdesc->natts < fnumber || fnumber <= 0)
(gdb) where
#0 SPI_gettypeid (tupdesc=0x0, fnumber=1) at spi.c:501
#1 0x402946bf in exec_move_row (estate=0xdfbfcddc, rec=0x0, row=0x186420,
tup=0x0, tupdesc=0x0) at pl_exec.c:2640
#2 0x40292b71 in exec_stmt_select (estate=0xdfbfcddc, stmt=0x186600)
at pl_exec.c:1455
#3 0x40292252 in exec_stmt (estate=0xdfbfcddc, stmt=0x186600) at pl_exec.c:978
#4 0x402920ea in exec_stmts (estate=0xdfbfcddc, stmts=0x276410)
at pl_exec.c:920
#5 0x40292044 in exec_stmt_block (estate=0xdfbfcddc, block=0x186660)
at pl_exec.c:876
#6 0x402914c1 in plpgsql_exec_function (func=0x27b500, fcinfo=0x22b65c)
at pl_exec.c:381
#7 0x4028edb6 in plpgsql_call_handler (fcinfo=0x22b65c) at pl_handler.c:128
#8 0x83be1 in ExecMakeFunctionResult (fcache=0x22b648, arguments=0x22b058,
econtext=0x22b0f8, isNull=0xdfbfcf2b "", isDone=0xdfbfcf2c)
at execQual.c:807
#9 0x83c9a in ExecEvalFunc (funcClause=0x22b140, econtext=0x22b0f8,
isNull=0xdfbfcf2b "", isDone=0xdfbfcf2c) at execQual.c:901
#10 0x840e9 in ExecEvalExpr (expression=0x22b140, econtext=0x22b0f8,
isNull=0xdfbfcf2b "", isDone=0xdfbfcf2c) at execQual.c:1226
#11 0x843e1 in ExecTargetList (targetlist=0x22b1b0, nodomains=1,
:: snip ::
#24 0x9314e in main (argc=3, argv=0xdfbfdc3c) at main.c:171
(gdb) p tupdesc
$1 = 0x0
(gdb)