And here the backtrace of the corresponding core (this is on
NetBSD/amd64 8.99.15 with lang/python36 package of today pkgsrc-current):

    % gdb -core python3.6.core `which python3.6`
    Reading symbols from /usr/pkg/bin/python3.6...done.
    [New process 1]
    Core was generated by `python3.6'.
    Program terminated with signal SIGABRT, Aborted.
    #0  0x000076255932924a in _lwp_kill () from /usr/lib/libc.so.12
    (gdb) bt
    #0  0x000076255932924a in _lwp_kill () from /usr/lib/libc.so.12
    #1  0x0000762559328e65 in abort () at /usr/src/lib/libc/stdlib/abort.c:74
    #2  0x000076255a749d33 in Py_FatalError (msg=msg@entry=0x76255a7dea20 "Py_Initialize: can't initialize sys standard streams")
        at Python/pylifecycle.c:1462
    #3  0x000076255a74af4c in _Py_InitializeEx_Private (install_sigs=1, install_importlib=1) at Python/pylifecycle.c:450
    #4  0x000076255a764902 in Py_Main (argc=argc@entry=3, argv=argv@entry=0x76255ab01060) at Modules/main.c:700
    #5  0x0000000000400e2f in main (argc=3, argv=<optimized out>) at ./Programs/python.c:69
    (gdb) f 4
    #4  0x000076255a764902 in Py_Main (argc=argc@entry=3, argv=argv@entry=0x76255ab01060) at Modules/main.c:700
    700         Py_Initialize();
    (gdb) f 3
    #3  0x000076255a74af4c in _Py_InitializeEx_Private (install_sigs=1, install_importlib=1) at Python/pylifecycle.c:450
    450             Py_FatalError(
    (gdb) list
    445         if (_PyTraceMalloc_Init() < 0)
    446             Py_FatalError("Py_Initialize: can't initialize tracemalloc");
    447
    448         initmain(interp); /* Module __main__ */
    449         if (initstdio() < 0)
    450             Py_FatalError(
    451                 "Py_Initialize: can't initialize sys standard streams");
    452
    453         /* Initialize warnings. */
    454         if (PySys_HasWarnOptions()) {

Please let me know if any further information is needed and I will try
to help!

Thank you!