remove ambig in nondiff cumprod(::Vector{AbstractBool}) on julia 1.6

[oxinabox]

This doesn't reproduce locally for me.
And doesn't show up on never julia versions.
Possibly dispatch changed subtly to prevent this.
But lets see if it fixes it on CI

[oxinabox]

it fixed it., Yay.
Now lets see if someone reviews

[devmotion]

Looks good to me - the only question I have is whether you considered merging the rrules in

ChainRules.jl/src/rulesets/Base/mapreduce.jl

Lines 328 to 374 in b3f9f9b

	function rrule(::typeof(cumprod), x::AbstractVector{<:Real}; dims::Integer=1)
	y = cumprod(x; dims=dims) # does nothing unless dims == 1
	project_x = ProjectTo(x)
	function cumprod_pullback_1(dy_raw)
	dy = unthunk(dy_raw)
	dx_thunk = InplaceableThunk(
	dx -> if dims == 1
	∇cumprod!(dx, x, dy, y)
	else
	dx .+= dy
	end
	,
	@thunk project_x(if dims == 1
	∇cumprod(x, dy, y)
	else
	dy
	end)
	)
	return (NoTangent(), dx_thunk)
	end
	return y, cumprod_pullback_1
	end
	function rrule(::typeof(cumprod), x::AbstractArray{<:Real}; dims::Integer)
	y = cumprod(x; dims=dims)
	project_x = ProjectTo(x)
	function cumprod_pullback_2(dy_raw)
	dy = unthunk(dy_raw)
	dx_thunk = InplaceableThunk(
	dx -> if dims <= ndims(x)
	vald = Val(Int(dims))
	∇cumprod_dim!(dx, vald, x, dy, y)
	else
	dx .+= dy
	end
	,
	@thunk project_x(if dims <= ndims(x)
	vald = Val(Int(dims))
	∇cumprod_dim(vald, x, dy, y)
	else
	dy
	end)
	)
	return (NoTangent(), dx_thunk)
	end
	return y, cumprod_pullback_2
	end

as an alternative. As far as I can tell, this would be an alternative fix for the ambiguity?

[oxinabox]

Merging this over #784 as it is passing CI already.
Which empirically suggests it is simpler