stress/c2g are non-reproducible when multi-threaded due to races in random-lut accesses

Hi folks,

I have noticed white lines are created when I use the colour to grey desaturation filter from the command line.

For example, when I do gegl River_Shannon_from_Drumsna_bridge.jpg -o output.png -- c2g radius=1300 samples=4 iterations=23 on the image of the river shannon https://en.wikipedia.org/wiki/River_Shannon#/media/File:River_Shannon_from_Drumsna_bridge.jpg one obtains the artifact white lines on the left side of the image:

For some reason, if I apply the same effect and parameters in GIMP the white lines are not there (as one would expect).

I am using the git version of gegl in Antergos OS (arch based) built a two or three days ago (how do I check which gegl version I am using?)

Thanks!

ps: Console output to the gegl River_Shannon_from_Drumsna_bridge.jpg -o output.png -- c2g radius=1300 samples=4 iterations=23 command:

(gegl:2555): GEGL-WARNING **: 21:57:10.627: (gegl-tile-handler-cache.c:1075):gegl_tile_cache_destroy: runtime check failed: (g_queue_is_empty (&cache_queue))
EEEEeEeek! 1 GeglBuffers leaked