-s 512 doesn't work

[agoode]

$ PYTHONPATH=$HOME/openslide-git/openslide-python/build/lib ~/openslide-git/openslide-python/examples/deepzoom/deepzoom-tile.py -s 512 ~/openslide-testdata/Mirax/CMU-2.mrxs 
Suspension not allowed here
Process TileWorker:
Traceback (most recent call last):
  File "/usr/lib64/python2.7/multiprocessing/process.py", line 232, in _bootstrap
    self.run()
  File "/home/agoode/openslide-git/openslide-python/examples/deepzoom/deepzoom-tile.py", line 62, in run
    tile.save(outfile, optimize=True, quality=90)
  File "/usr/lib64/python2.7/site-packages/PIL/Image.py", line 1439, in save
    save_handler(self, fp, filename)
  File "/usr/lib64/python2.7/site-packages/PIL/JpegImagePlugin.py", line 471, in _save
    ImageFile._save(im, fp, [("jpeg", (0,0)+im.size, 0, rawmode)])
  File "/usr/lib64/python2.7/site-packages/PIL/ImageFile.py", line 501, in _save
    raise IOError("encoder error %d when writing image file" % s)
IOError: encoder error -2 when writing image file