SparseArrays.nzrange could benefit from a Base.@propagate_inbounds

[vtjnash]

When doing the following type of iteration over SparseArrays, I was expecting that no bound checks would be added.
However nzrange does add some because it doesn't have Base.@propagate_inbounds

@inbounds for j = 1:n
  @inbounds for idx in nzrange(X,j)
  end
end

The exact semantics of @inbounds here is somewhat unclear: my intuitive feeling is that the @inbounds of the inner loop doesn't include the nzrange(X,j) and only the loop body. This is not how @inbounds is implemented however.

originally posted at JuliaLang/julia#42553 by @tomhaber. I make no claim whether this issue is valid.