Turtle module produces double paths

[byorgey]

This code:

import           Control.Monad             (replicateM_)
import           Diagrams.Prelude
import           Diagrams.TwoD.Path.Turtle
import           Text.Groom

main = putStrLn . groom $ mount 7 10

f d = forward (72 * d / 6)
r = right 90

draw p = sketchTurtle $ do
  setPenWidth 0.1
  p
  closeCurrent

mount w h = draw $ replicateM_ 2 $ do
  f (fromIntegral w * 6 + 1) ; r
  f (fromIntegral h * 6 + 1) ; r

produces this output:

Path{pathTrails =
       [Loc{loc = P (0.0 & 0.0),
            obj =
              Trail
                (Loop
                   (SegTree{getSegTree =
                              fromList
                                [Linear (OffsetClosed (516.0 & 0.0)),
                                 Linear (OffsetClosed (4.482207284879313e-14 & (-732.0))),
                                 Linear (OffsetClosed ((-516.0) & (-6.319177483600342e-14))),
                                 Linear (OffsetClosed ((-1.3446621854637937e-13) & 732.0))]})
                   (Linear OffsetOpen))},
        Loc{loc = P (0.0 & 0.0),
            obj =
              Trail
                (Line
                   (SegTree{getSegTree =
                              fromList
                                [Linear (OffsetClosed (516.0 & 0.0)),
                                 Linear (OffsetClosed (4.482207284879313e-14 & (-732.0))),
                                 Linear (OffsetClosed ((-516.0) & (-6.319177483600342e-14))),
                                 Linear (OffsetClosed ((-1.3446621854637937e-13) & 732.0))]}))}]}

As you can see this consists of a line and a loop tracing the same path.