Removed redundant check

Loop takes care of it already

lib/pure/algorithm.nim

@@ -240,8 +240,6 @@ template sortedByIt*(seq1, op: expr): expr =
 proc isSorted*[T](a: openarray[T],
                  cmp: proc(x, y: T): int {.closure.},
                  order = SortOrder.Ascending): bool =
-  if len(a) <= 1: return true
-
   result = true
   for i in 0..<len(a)-1:
     if cmp(a[i],a[i+1]) * order > 0: