'Mono' scheme doesn't work on ubuntu 13.10

ubuntu 12.04 & brew is fine...
ubuntu@ip-80-0-0-154:~/proj/python/mason⟫ ./tilerenderer.py themes/Brick2/mono.cfg.py  -t 1
======================================================================
Parallel Tile Renderer (v0.9.5), please be very patient.
Press CTRL+C to break render process...
======================================================================
Test configuration, turn off test to start rendering.
[INFO/MainProcess] Loading renderer configuration: "themes/Brick2/mono.cfg.py"
[INFO/MainProcess] Logging to: "/home/ubuntu/proj/python/mason/render.log"
[INFO/MainProcess] Rendering mode is "hybrid"
[INFO/MainProcess] Rendering level: [2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19]
[INFO/MainProcess] Rendering envelope: (-180, -85.06, 180, 85.06)
[INFO/MainProcess] Rendering tile list:
[INFO/MainProcess] Rendering using meta tile stride=1
[INFO/MainProcess] Rendering using 2 workers on 2 cores
[INFO/MainProcess] Test render 1 Tiles
[INFO/MainProcess] Rendering MetaTileIndex(2/0/0@1)...
[INFO/MainProcess] MetaTileIndex(2/0/0@1) rendered in 1.0964s
Traceback (most recent call last):
  File "./tilerenderer.py", line 402, in <module>
    main()
  File "./tilerenderer.py", line 375, in main
    test_render(renderer, options)
  File "./tilerenderer.py", line 342, in test_render
    metatile = renderer.render_metatile(index)
  File "/home/ubuntu/proj/python/mason/mason/config.py", line 147, in render_metatile
    metatile = self._renderer.render(context)
  File "/home/ubuntu/proj/python/mason/mason/renderer/node.py", line 83, in render
    return RenderNode.render(self, context)
  File "/home/ubuntu/proj/python/mason/mason/renderer/tree.py", line 48, in render
    result = self._render_imp(context, sources)
  File "/home/ubuntu/proj/python/mason/mason/renderer/node.py", line 90, in _render_imp
    metatile = self._render_metatile(metatile_index, metatile_sources)
  File "/home/ubuntu/proj/python/mason/mason/renderer/node.py", line 342, in _render_metatile
    data_stream = self._composer.compose(images)
  File "/home/ubuntu/proj/python/mason/mason/composer/imagemagick.py", line 125, in compose
    output=stderr)
mason.composer.imagemagick.ImageMagickError: -6
$ convert -quiet -limit thread 1 ( /tmp/mgktle$base-yTPkVE.png -ordered-dither o4x4,4 ) ( ( /tmp/mgktle$road-I4oeSo.png -ordered-dither o4x4,8 ) ( /tmp/mgktle$halo-Ye6rxy.png +level-colors #ebe9e6 ) -comp
ose Atop -composite ) -compose Over -composite ( /tmp/mgktle$label-cxXyVE.png -brightness-contrast +10 ( +clone -channel A -morphology HMT LineJunctions -morphology Dilate Disk:1 +channel ) -compose Multi
ply -composite ) -compose Over -composite -brightness-contrast -15x-10 ./themes/Brick2/mapnik/duotone/Bl-for-dark-cg9-cg2.bmp -clut -dither none -colors 128 png:-
convert: magick/cache-view.c:477: GetCacheViewAuthenticPixels: Assertion `id < (int) cache_view->number_threads' failed.

[INFO/MainProcess] process shutting down
[DEBUG/MainProcess] running all "atexit" finalizers with priority >= 0
[DEBUG/MainProcess] running the remaining "atexit" finalizers
Kotaimen / maps-Brick

'Mono' scheme doesn't work on ubuntu 13.10 #8
