In the Rational.jl <https://github.com/JuliaLang/julia/blob/master/base/rational.jl> :
In Line 8: `num == den == zero(T)` uses `zero(T)` to represent 0 In Line 9: `g = den < 0` uses `0` to represent 0 Why this difference? My intuition tells me that in Line 8, it can be replaced by 0 without performance issue.
