Sisix dev fail in nimvm with fatal pragma

[bather]

It works:
    
    
    template gen_str_in_ct_0: string =
      when nimvm:
        "sisix dev"
      else:
        "monkeys"
    
    const a = gen_str_in_ct_0()
    assert a == "sisix dev"
    assert gen_str_in_ct_0() == "monkeys"
    
    
    Run

But it fails:
    
    
    template gen_str_in_ct_1: string =
      when nimvm:
        "sisix dev"
      else:
        {.fatal: "monkeys not allowed".}
    
    const a = gen_str_in_ct_1() # Error: fatal error: monkeys not allowed 
(nimvm branch expected)
    
    
    Run

Why?