PolygonPatternSymbolizer can't find file that exists

[zenitraM]

ubuntu@bpi02:~/www/node-windshaft/shared/log$ grep PolygonPatternSymbolizer node-windshaft.log
[2015-05-13 00:50:38.687] [ERROR] console - [TILE RENDER ERROR] -- 400: Error: file could not be found: '/home/ubuntu/tile_assets/cache/5ee9bb05-park-halftone-1.png' in style 'layer4' in PolygonPatternSymbolizer
[2015-05-13 07:29:45.846] [ERROR] console - [TILE RENDER ERROR] -- 400: Error: file could not be found: '/home/ubuntu/tile_assets/cache/5ee9bb05-park-halftone-1.png' in style 'layer4' in PolygonPatternSymbolizer
[2015-05-13 07:30:05.941] [ERROR] console - [TILE RENDER ERROR] -- 400: Error: file could not be found: '/home/ubuntu/tile_assets/cache/5ee9bb05-park-halftone-1.png' in style 'layer4' in PolygonPatternSymbolizer
[2015-05-13 07:30:05.945] [ERROR] console - [TILE RENDER ERROR] -- 400: Error: file could not be found: '/home/ubuntu/tile_assets/cache/5ee9bb05-park-halftone-1.png' in style 'layer4' in PolygonPatternSymbolizer
[2015-05-13 13:59:05.941] [ERROR] console - [TILE RENDER ERROR] -- 400: Error: file could not be found: '/home/ubuntu/tile_assets/cache/5ee9bb05-park-halftone-1.png' in style 'layer4' in PolygonPatternSymbolizer
[2015-05-13 14:19:18.916] [ERROR] console - [TILE RENDER ERROR] -- 400: Error: file could not be found: '/home/ubuntu/tile_assets/cache/5ee9bb05-park-halftone-1.png' in style 'layer4' in PolygonPatternSymbolizer

but:

ubuntu@bpi02:~/www/node-windshaft/shared/log$ stat /home/ubuntu/tile_assets/cache/5ee9bb05-park-halftone-1.png
  File: `/home/ubuntu/tile_assets/cache/5ee9bb05-park-halftone-1.png'
  Size: 4413        Blocks: 16         IO Block: 4096   regular file
Device: ca01h/51713d    Inode: 265349      Links: 1
Access: (0644/-rw-r--r--)  Uid: ( 1000/  ubuntu)   Gid: ( 1000/  ubuntu)
Access: 2015-05-12 22:48:49.526628009 +0000
Modify: 2015-05-12 22:48:50.134630351 +0000
Change: 2015-05-12 22:48:50.134630351 +0000
 Birth: -
ubuntu@bpi02:~/www/node-windshaft/shared/log$ file /home/ubuntu/tile_assets/cache/5ee9bb05-park-halftone-1.png
/home/ubuntu/tile_assets/cache/5ee9bb05-park-halftone-1.png: PNG image data, 24 x 24, 8-bit/color RGB, non-interlaced

The file exists, is a PNG, and according to the modify time it was last modified before when that error was thrown.

(This is the basemap asset we were blaming Dropbox about previously, but now it's hosted on S3)

[rochoa]

This should be fixed as per CartoDB/Windshaft#339