I think you are right. Go `big.Mod` should be Euclidean (i.e. `x % y` follows `y`'s sign) so the code is redundant. It doesn't seem to be required to run in con

I think you are right. Go `big.Mod` should be Euclidean (i.e. `x % y` follows `y`'s sign) so the code is redundant. It doesn't seem to be required to run in constant time (if so we won't have `if` at all), probably the committer wanted a minimal change?