Keep only a single expression tree after if

[korenmiklos]

y > 0 && x < 0 is a single expression, not a tuple

Expr
  head: Symbol &&
  args: Array{Any}((2,))
    1: Expr
      head: Symbol call
      args: Array{Any}((3,))
        1: Symbol >
        2: Symbol y
        3: Int64 0
    2: Expr
      head: Symbol call
      args: Array{Any}((3,))
        1: Symbol <
        2: Symbol x
        3: Int64 0