#0  0x00007ffff60d6f18 in NsEnsembleImplementationCmdNR (
    clientData=<optimized out>, interp=interp@entry=0x7fffec008c40, objc=2, 
    objv=0xa3e990)
    at /home/sean/tmp/tcl/src/tcl8.6.0/generic/tclEnsemble.c:1657
#1  0x00007ffff608056a in Tcl_NRCallObjProc (interp=0x7fffec008c40, 
    objProc=objProc@entry=0x7ffff60d6e81 <NsEnsembleImplementationCmdNR>, 
    clientData=<optimized out>, objc=<optimized out>, objv=<optimized out>)
    at /home/sean/tmp/tcl/src/tcl8.6.0/generic/tclBasic.c:8150
#2  0x00007ffff60d6d3b in NsEnsembleImplementationCmd (
    clientData=<optimized out>, interp=<optimized out>, objc=<optimized out>, 
    objv=<optimized out>)
    at /home/sean/tmp/tcl/src/tcl8.6.0/generic/tclEnsemble.c:1616
#3  0x00007ffff63c028e in ip_rbNamespaceObjCmd (clientData=<optimized out>, 
    interp=0x7fffec008c40, objc=2, objv=0xa3e990) at tcltklib.c:6038
#4  0x00007ffff63bb36f in invoke_tcl_proc (arg=arg@entry=140737275646640)
    at tcltklib.c:8507
#5  0x00007ffff7a3980c in rb_protect (
    proc=proc@entry=0x7ffff63bb2c8 <invoke_tcl_proc>, 
    data=data@entry=140737275646640, state=state@entry=0x7ffff352526c)
    at eval.c:719
#6  0x00007ffff63bcc5b in ip_invoke_core (interp=16440400, objc=2, 
    objv=0xa3e990) at tcltklib.c:8676
#7  0x00007ffff63bdbf3 in invoke_queue_handler (evPtr=evPtr@entry=0xa3d610, 
    flags=flags@entry=-3) at tcltklib.c:9030
#8  0x00007ffff6115110 in Tcl_ServiceEvent (flags=flags@entry=-3)
    at /home/sean/tmp/tcl/src/tcl8.6.0/generic/tclNotify.c:670
#9  0x00007ffff611532b in Tcl_DoOneEvent (flags=-3)
    at /home/sean/tmp/tcl/src/tcl8.6.0/generic/tclNotify.c:907
#10 0x00007ffff63ba599 in call_DoOneEvent_core (flag_val=<optimized out>)
    at tcltklib.c:2011
#11 0x00007ffff63b8eac in tk_funcall (
    func=func@entry=0x7ffff63ba589 <call_DoOneEvent_core>, argc=argc@entry=0, 
    argv=argv@entry=0x0, obj=obj@entry=18446744073709551611) at tcltklib.c:7137
#12 0x00007ffff63b964f in call_DoOneEvent (
    flag_val=flag_val@entry=18446744073709551611) at tcltklib.c:2026
#13 0x00007ffff7a3980c in rb_protect (
    proc=proc@entry=0x7ffff63b9632 <call_DoOneEvent>, 
    data=18446744073709551611, state=state@entry=0x7ffff35256c4) at eval.c:719
#14 0x00007ffff63c4af4 in lib_eventloop_core (interp=0x0, check_var=0x0, 
    update_flag=0, check_root=1) at tcltklib.c:2364
#15 lib_eventloop_main_core (args=args@entry=140737154396592)
    at tcltklib.c:2559
#16 0x00007ffff7a39988 in rb_ensure (
    b_proc=b_proc@entry=0x7ffff63c4516 <lib_eventloop_main_core>, 
    data1=data1@entry=140737154396592, 
    e_proc=e_proc@entry=0x7ffff63c40c1 <lib_eventloop_ensure>, 
    data2=data2@entry=140737154396592) at eval.c:744
#17 0x00007ffff63c0aa7 in lib_eventloop_launcher (check_root=1, 
    update_flag=update_flag@entry=0, check_var=check_var@entry=0x0, 
    interp=interp@entry=0x0) at tcltklib.c:2719
#18 0x00007ffff63c1126 in lib_mainloop (argc=argc@entry=1, 
    argv=argv@entry=0x7ffff3527070, self=self@entry=16440400)
    at tcltklib.c:2740
#19 0x00007ffff63c11a1 in ip_mainloop (argc=1, argv=0x7ffff3527070, 
    self=16440400) at tcltklib.c:2764
#20 0x00007ffff7b0d8ee in call_cfunc (func=0x7ffff63c112b <ip_mainloop>, 
    recv=recv@entry=16440400, len=<optimized out>, argc=argc@entry=1, 
    argv=<optimized out>) at vm_insnhelper.c:317
#21 0x00007ffff7b1b6b7 in vm_call_cfunc (me=0x78cbd0, blockptr=0x0, 
    recv=<optimized out>, num=1, reg_cfp=0x7ffff3626f08, th=0xfbb570)
    at vm_insnhelper.c:404
#22 vm_call_method (th=th@entry=0xfbb570, cfp=cfp@entry=0x7ffff3626f08, 
    num=num@entry=1, blockptr=0x0, flag=flag@entry=0, id=id@entry=16096, 
    me=0x78cbd0, recv=recv@entry=16440400) at vm_insnhelper.c:530
#23 0x00007ffff7b12c1b in vm_exec_core (th=th@entry=0xfbb570, 
    initial=initial@entry=0) at insns.def:1018
#24 0x00007ffff7b16b9f in vm_exec (th=th@entry=0xfbb570) at vm.c:1236
#25 0x00007ffff7b17b0b in invoke_block_from_c (th=0xfbb570, block=0xfbf940, 
    self=16441200, argc=0, argv=0xfadcd8, blockptr=0x0, cref=0x0) at vm.c:640
#26 0x00007ffff7b17beb in rb_vm_invoke_proc (th=0x7ffff63a71c0 <tclListType>, 
    th@entry=0x7ffff3524ba8, proc=0xfbf940, self=16441200, argc=0, 
    argv=0xfadcd8, blockptr=blockptr@entry=0x0) at vm.c:686
#27 0x00007ffff7b26ab3 in thread_start_func_2 (th=th@entry=0xfbb570, 
    stack_start=0x7ffff3527000) at thread.c:453
#28 0x00007ffff7b26ddf in thread_start_func_1 (th_ptr=0xfbb570)
    at thread_pthread.c:654
#29 0x00007ffff741fe0f in start_thread () from /usr/lib/libpthread.so.0
#30 0x00007ffff771cefd in clone () from /usr/lib/libc.so.6