es 0.84 assertion failure under UTek 4.0

[trost@cloud.rain.com (Bill Trost)]

[For those who don't know, UTek is the operating system for the
Tektronix 431[5-9] series 68020-based workstations]

Ugh...I got this assertion failure after a few simple commands.
However, I'm running with the path-caching stuff and an experimental
history mechanism.

    match.c:139: assertion failed (q != ((void *)0))

The great part of this is -- the call stack is over 100 frames deep!
I'm providing a few variables of interest, and some portion of the
call stack.  I'd appreciate it if someone pointed to where I should
look next to see where this problem's coming from.

Oh, yes -- this is with gcc 1.36 (best I can do at the moment), with
or without optimization.  Oddly enough, using gdb breakpoints changes
the program's behavior if the program is compiled without
optimization, but not when it's compiled *with* it.  Urph.

(gdb) p subject
$22 = (struct List *) 0x6e0d4
(gdb) p pattern
$23 = (struct List *) 0x6e0c8
(gdb) p quote
$24 = (struct StrList *) 0x6b3d0
(gdb) p s
$25 = (struct List *) 0x6e0d4
(gdb) p p
$26 = (struct List *) 0x74964
(gdb) p q
$27 = (struct StrList *) 0x0
(gdb) p *p
$28 = {term = 0x73f00, next = 0x0}
(gdb) p *p->term
$29 = {str = 0x0, closure = 0x74030}
(gdb) where
#0  0x2206c in abort ()
#1  0xea32 in listmatch (subject=(struct List *) 0x6e0d4, pattern=(struct List *) 0x6e0c8, quote=(struct StrList *) 0x6b3d0) (match.c line 139)
#2  0x50b8 in walk (tree0=(struct Tree *) 0x5e5e0, binding0=(struct Binding *) 0x69f7c, flags=0) (eval.c line 253)
#3  0x3da2 in eval (list=(struct List *) 0x6b07c, binding0=(struct Binding *) 0x6af88, flags=0) (eval.c line 111)
#4  0x4ff4 in walk (tree0=(struct Tree *) 0x1e3ca, binding0=(struct Binding *) 0x6af88, flags=0) (eval.c line 241)
#5  0x3da2 in eval (list=(struct List *) 0x6b058, binding0=(struct Binding *) 0x0, flags=0) (eval.c line 111)
#6  0x461c in eval1 (term=(struct Term *) 0x6afc8, flags=0) (eval.c line 186)
#7  0xf8c8 in prim_if (...) (...)
#8  0x14802 in prim (...) (...)
#9  0x3d7c in eval (list=(struct List *) 0x6b04c, binding0=(struct Binding *) 0x6af88, flags=0) (eval.c line 108)
#10 0x4ff4 in walk (tree0=(struct Tree *) 0x1e3f2, binding0=(struct Binding *) 0x6af88, flags=0) (eval.c line 241)
#11 0x11d7e in prim_noreturn (...) (...)
...
#97 0x4ff4 in walk (tree0=(struct Tree *) 0x21b64, binding0=(struct Binding *) 0x53960, flags=4) (eval.c line 241)
#98 0x3da2 in eval (list=(struct List *) 0x53988, binding0=(struct Binding *) 0x53960, flags=4) (eval.c line 111)
#99 0x4ff4 in walk (tree0=(struct Tree *) 0x21bc0, binding0=(struct Binding *) 0x538f0, flags=4) (eval.c line 241)
#100 0x3f0a in eval (list=(struct List *) 0x21bfc, binding0=(struct Binding *) 0x0, flags=4) (eval.c line 128)
#101 0xc18c in runinput (...) (...)
#102 0xc310 in runfd (...) (...)
#103 0xe224 in main (...) (...)