ParStream.filter followed by ParStream.mapi gives incorrect results when iterated

[dsyme]

I believe ParStream.iter needs to check for if stream.PreserveOrdering then...

Repro:

ParStream.ofArray [| 101 .. 201 |] 
  |> ParStream.filter (fun x -> x % 2 = 0) 
  |> ParStream.mapi (fun i x -> (i,x)) 
  |> ParStream.iter (printfn "%A")

gives

(25, 126)
(1, 102)
(51, 152)
(3, 104)
(27, 128)
(53, 154)
(5, 106)
(29, 130)
(31, 132)
(7, 108)
(55, 156)
(33, 134)
(9, 110)
(57, 158)
(35, 136)
(11, 112)
(59, 160)
(37, 138)
(13, 114)
(15, 116)
(39, 140)
(61, 162)
(17, 118)
(41, 142)
(63, 164)
(19, 120)
(43, 144)
(65, 166)
(21, 122)
(45, 146)
(23, 124)
(47, 148)
(67, 168)
(75, 176)
(49, 150)
(69, 170)
(77, 178)
(71, 172)
(79, 180)
(73, 174)
(81, 182)
(83, 184)
(85, 186)
(87, 188)
(89, 190)
(91, 192)
(93, 194)
(95, 196)
(97, 198)
(99, 200)