dbx output:

Again: help appreciated.

(dbx) run  -X tracemalloc
Objects/genobject.c:127: _PyObject_GC_TRACK: Assertion "!(((PyGC_Head *)(op)-1)->_gc_next != 0)" failed: object already tracked by the garbage collector
Enable tracemalloc to get the memory block allocation traceback

object address  : 30085150
object refcount : 0
object type     : 20014188
object type name: generator
object repr     : <refcnt 0 at 30085150>

Fatal Python error: _PyObject_AssertFailed: _PyObject_AssertFailed
Python runtime state: core initialized

Current thread 0x00000001 (most recent call first):
  File "<frozen importlib._bootstrap_external>", line 1593 in _setup
  File "<frozen importlib._bootstrap_external>", line 1634 in _install
  File "<frozen importlib._bootstrap>", line 1189 in _install_external_importers

IOT/Abort trap in pthread_kill at 0xd057a02c ($t1)
0xd057a02c (pthread_kill+0xac) 80410014            lwz   r2,0x14(r1)
(dbx) where
pthread_kill(??, ??) at 0xd057a02c
_p_raise(??) at 0xd0579408
raise.raise(??) at 0xd0123344
abort() at 0xd0189918
IPRA.$fatal_error(stream = 0x2006e370, header = 805397344, prefix = (nil), msg = (nil), status = 0), line 2183 in "pylifecycle.c"
_Py_FatalErrorFunc(func = "", msg = "\n"), line 2283 in "pylifecycle.c"
_PyObject_AssertFailed(obj = 0x30086038, expr = "", msg = (nil), file = "\177\200", line = 537322352, function = ""), line 2195 in "object.c"
gen_dealloc(gen = 0x2004af44), line 65532 in "pycore_object.h"
_Py_Dealloc(op = 0x00000013), line 2206 in "object.c"
unnamed block in _PyEval_EvalFrameDefault(tstate = 0x2006e370, f = 0x30023b0c, throwflag = 804397120), line 1046 in "object.h"
_PyEval_EvalFrameDefault(tstate = 0x2006e370, f = 0x30023b0c, throwflag = 804397120), line 1046 in "object.h"
unnamed block in IPRA.$function_code_fastcall(tstate = 0x2004af44, co = 0x20030848, args = 0x30066f7c, nargs = 805735610, globals = 0x30068cb8), line 40 in "pycore_ceval.h"
IPRA.$function_code_fastcall(tstate = 0x2004af44, co = 0x20030848, args = 0x30066f7c, nargs = 805735610, globals = 0x30068cb8), line 40 in "pycore_ceval.h"
_PyFunction_Vectorcall(func = 0x00000006, stack = 0x30083898, nargsf = 804397328, kwnames = 0x3006e110), line 366 in "call.c"
unnamed block in _PyEval_EvalFrameDefault(tstate = 0x2004af44, f = 0xffffffe2, throwflag = 804397584), line 739 in "abstract.h"
_PyEval_EvalFrameDefault(tstate = 0x2004af44, f = 0xffffffe2, throwflag = 804397584), line 739 in "abstract.h"
unnamed block in IPRA.$function_code_fastcall(tstate = 0x2004af44, co = 0x20030848, args = 0x30023b14, nargs = 805682254, globals = 0x3005bc38), line 40 in "pycore_ceval.h"
IPRA.$function_code_fastcall(tstate = 0x2004af44, co = 0x20030848, args = 0x30023b14, nargs = 805682254, globals = 0x3005bc38), line 40 in "pycore_ceval.h"
_PyFunction_Vectorcall(func = 0x00000005, stack = 0x3005da78, nargsf = 804397856, kwnames = 0xdeadbeef), line 366 in "call.c"
unnamed block in _PyEval_EvalFrameDefault(tstate = 0x100fbeb8, f = 0x2006e370, throwflag = 804398128), line 739 in "abstract.h"
_PyEval_EvalFrameDefault(tstate = 0x100fbeb8, f = 0x2006e370, throwflag = 804398128), line 739 in "abstract.h"
unnamed block in IPRA.$function_code_fastcall(tstate = 0x10073f50, co = 0x2000a350, args = 0x20011a58, nargs = 537167132, globals = 0x30049118), line 40 in "pycore_ceval.h"
IPRA.$function_code_fastcall(tstate = 0x10073f50, co = 0x2000a350, args = 0x20011a58, nargs = 537167132, globals = 0x30049118), line 40 in "pycore_ceval.h"
_PyFunction_Vectorcall(func = 0xd98069bf, stack = 0x00000008, nargsf = 4029698048, kwnames = 0x2006e370), line 366 in "call.c"
IPRA.$_PyObject_CallFunctionVa(tstate = 0x100f6cb0, callable = (nil), format = "/\362%\340-zj\244^P^O\242\234/\362&\340^\220K\250 ^D\205^\^PCl\243/\362&\340", va = "", is_size_t = 272852043), line 62 in "abstract.h"
IPRA.$callmethod(tstate = 0x100fa29c, callable = 0x2ff226e0, format = (invalid char ptr (0x5e904ba8)), va = "", is_size_t = 272854179), line 614 in "call.c"
PyObject_CallMethod(obj = 0x102c266c, name = "", format = "", ... = 0x20077748, 0xffff, 0x20077748, 0x20, 0x10), line 634 in "call.c"
init_importlib_external(tstate = 0xdeadbeef), line 209 in "pylifecycle.c"
IPRA.$init_interp_main(tstate = 0x00000001), line 993 in "pylifecycle.c"
pyinit_main(tstate = 0x2003c984), line 1097 in "pylifecycle.c"
Py_InitializeFromConfig(config = 0xf078b380), line 1141 in "pylifecycle.c"
pymain_init(args = 0x00000001), line 66 in "main.c"
pymain_main(args = 0x00000003), line 653 in "main.c"
Py_BytesMain(argc = -559038737, argv = 0xdeadbeef), line 686 in "main.c"
python.main(argc = 0, argv = (nil)), line 16 in "python.c"