(A) keep_dims=true,  axes 1 then 2 on [1,2,3,4]: fused axes = {1,3}   reference {1,2}
(A') keep_dims=true, axes 1 then 3 on [1,2,3,4]: EXCEPTION: vector   reference {1,3}
(B) keep_dims=false, axes 1 then -2 on [1,64,20,32]: fused axes = {1,3}   reference {1,2}
(B') keep_dims=false, axes 1 then -1 on [1,64,20,32]: EXCEPTION: vector   reference {1,3}
(ctl) keep_dims=false, axes 1 then 1 on [1,64,20,32]: fused axes = {1,2}   reference {1,2}
