Panic when running t/spec/S32-exceptions/misc.t under stress, i.e. small nursery

gistfile1.txt

    ./perl6-gdb-m t/spec/S32-exceptions/misc.rakudo.moar
    ...
    (gdb) r
    Starting program: /home/dilbert/repos/rakudo/install/bin/moar --execname=./perl6-gdb-m --libpath=. --libpath=blib --libpath=/home/dilbert/repos/rakudo/install/share/nqp/lib --libpath=/home/dilbert/repos/rakudo/install/share/nqp/lib --libpath=/home/dilbert/repos/rakudo/install/share/nqp/lib /home/dilbert/repos/rakudo/perl6.moarvm --nqp-lib=blib t/spec/S32-exceptions/misc.rakudo.moar
    [Thread debugging using libthread_db enabled]
    Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
    [New Thread 0x7ffff6768700 (LWP 6747)]
    1..450
        1..3
        ok 1 - '42 +' died
        ok 2 - right exception type (Exception)
    ...
    ok 208 - did we throws-like X::Str::Trans::InvalidArg?
        1..4
    [Switching to Thread 0x7ffff6768700 (LWP 6747)]
    
    Thread 2 "moar" hit Breakpoint 1, MVM_panic (exitCode=exitCode@entry=1, messageFormat=messageFormat@entry=0x7ffff77840a0 "Must not GC when in the specializer/JIT\n") at src/core/exceptions.c:827
    827	void MVM_panic(MVMint32 exitCode, const char *messageFormat, ...) {
    (gdb) bt
    #0  MVM_panic (exitCode=exitCode@entry=1, messageFormat=messageFormat@entry=0x7ffff77840a0 "Must not GC when in the specializer/JIT\n") at src/core/exceptions.c:827
    #1  0x00007ffff7670adb in run_gc (tc=tc@entry=0x68e0a0, what_to_do=what_to_do@entry=1 '\001') at src/gc/orchestrate.c:388
    #2  0x00007ffff7670c57 in MVM_gc_enter_from_interrupt (tc=tc@entry=0x68e0a0) at src/gc/orchestrate.c:611
    #3  0x00007ffff7670f0b in MVM_gc_mark_thread_blocked (tc=tc@entry=0x68e0a0) at src/gc/orchestrate.c:290
    #4  0x00007ffff76b1569 in MVM_reentrantmutex_lock (tc=tc@entry=0x68e0a0, rm=<optimized out>) at src/6model/reprs/ReentrantMutex.c:136
    #5  0x00007ffff76c6f49 in MVM_serialization_demand_object (tc=tc@entry=0x68e0a0, sc=<optimized out>, idx=4) at src/6model/serialization.c:2743
    #6  0x00007ffff76c1cd8 in MVM_sc_get_object (tc=tc@entry=0x68e0a0, sc=<optimized out>, idx=idx@entry=4) at src/6model/sc.c:193
    #7  0x00007ffff76e47b1 in fix_wval (inlinee=0x7ffff04bee60, to_fix=0x7ffff07cf618, to_fix=0x7ffff07cf618, inliner=0x7ffff1851cd0, tc=0x7ffff07cfc88) at src/spesh/inline.c:227
    #8  merge_graph (tc=tc@entry=0x68e0a0, inliner=inliner@entry=0x7ffff1851cd0, inlinee=inlinee@entry=0x7ffff04bee60, inlinee_sf=inlinee_sf@entry=0x12293c8, invoke_bb=invoke_bb@entry=0x7ffff071bfc8, 
        invoke_ins=invoke_ins@entry=0x7ffff07182f8, code_ref_reg=..., inline_boundary_handler=<optimized out>) at src/spesh/inline.c:429
    #9  0x00007ffff76e50a9 in MVM_spesh_inline (tc=tc@entry=0x68e0a0, inliner=inliner@entry=0x7ffff1851cd0, call_info=call_info@entry=0x7ffff6767990, invoke_bb=invoke_bb@entry=0x7ffff071bfc8, 
        invoke_ins=invoke_ins@entry=0x7ffff07182f8, inlinee=inlinee@entry=0x7ffff04bee60, inlinee_sf=0x12293c8, code_ref_reg=...) at src/spesh/inline.c:943
    #10 0x00007ffff76de67e in optimize_call (tc=tc@entry=0x68e0a0, g=g@entry=0x7ffff1851cd0, bb=bb@entry=0x7ffff071bfc8, ins=ins@entry=0x7ffff07182f8, p=p@entry=0x7ffff07c4e50, callee_idx=callee_idx@entry=1, 
        arg_info=0x7ffff6767990) at src/spesh/optimize.c:1715
    #11 0x00007ffff76df90e in optimize_bb_switch (tc=tc@entry=0x68e0a0, g=g@entry=0x7ffff1851cd0, bb=bb@entry=0x7ffff071bfc8, p=p@entry=0x7ffff07c4e50) at src/spesh/optimize.c:2129
    #12 0x00007ffff76e0e53 in optimize_bb (p=0x7ffff07c4e50, bb=0x7ffff071bfc8, g=0x7ffff1851cd0, tc=0x68e0a0) at src/spesh/optimize.c:2327
    #13 optimize_bb (p=0x7ffff07c4e50, bb=0x7ffff071b848, g=0x7ffff1851cd0, tc=0x68e0a0) at src/spesh/optimize.c:2331
    #14 optimize_bb (p=0x7ffff07c4e50, bb=0x7ffff071b668, g=0x7ffff1851cd0, tc=0x68e0a0) at src/spesh/optimize.c:2331
    #15 optimize_bb (tc=0x68e0a0, g=0x7ffff1851cd0, bb=0x7ffff071b428, p=0x7ffff07c4e50) at src/spesh/optimize.c:2331
    #16 0x00007ffff76e11f2 in optimize_bb (p=0x7ffff07c4e50, bb=0x7ffff071ab88, g=0x7ffff1851cd0, tc=0x68e0a0) at src/spesh/optimize.c:2331
    #17 MVM_spesh_optimize (tc=tc@entry=0x68e0a0, g=g@entry=0x7ffff1851cd0, p=p@entry=0x7ffff07c4e50) at src/spesh/optimize.c:2579
    #18 0x00007ffff76d81cd in MVM_spesh_candidate_add (tc=tc@entry=0x68e0a0, p=0x7ffff07c4e50) at src/spesh/candidate.c:62
    #19 0x00007ffff76e68e5 in worker (tc=0x68e0a0, callsite=<optimized out>, args=<optimized out>) at src/spesh/worker.c:16
    #20 0x00007ffff7655b51 in thread_initial_invoke (tc=0x68e0a0, data=<optimized out>) at src/core/threads.c:59
    #21 0x00007ffff762ec8e in MVM_interp_run (tc=0x1, tc@entry=0x68e0a0, initial_invoke=0x0, invoke_data=0x604098, invoke_data@entry=0x69f800) at src/core/interp.c:93
    #22 0x00007ffff7655bd6 in start_thread (data=0x69f800) at src/core/threads.c:87
    #23 0x00007ffff6b7c6ba in start_thread (arg=0x7ffff6768700) at pthread_create.c:333
    #24 0x00007ffff71a241d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109
    (gdb) info threads
      Id   Target Id         Frame 
      1    Thread 0x7ffff7fd9700 (LWP 6746) "moar" pthread_cond_wait@@GLIBC_2.3.2 () at ../sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:185
    * 2    Thread 0x7ffff6768700 (LWP 6747) "moar" MVM_panic (exitCode=exitCode@entry=1, messageFormat=messageFormat@entry=0x7ffff77840a0 "Must not GC when in the specializer/JIT\n") at src/core/exceptions.c:827
    (gdb) f 1
    #1  0x00007ffff7670adb in run_gc (tc=tc@entry=0x68e0a0, what_to_do=what_to_do@entry=1 '\001') at src/gc/orchestrate.c:388
    388	        MVM_panic(1, "Must not GC when in the specializer/JIT\n");
    (gdb) l
    383	
    384	    unsigned int interval_id;
    385	
    386	#if MVM_GC_DEBUG
    387	    if (tc->in_spesh)
    388	        MVM_panic(1, "Must not GC when in the specializer/JIT\n");
    389	#endif
    390	
    391	    /* Decide nursery or full collection. */
    392	    gen = tc->instance->gc_full_collect ? MVMGCGenerations_Both : MVMGCGenerations_Nursery;
    (gdb)