IndexError: index 5000 is out of bounds for axis 1 with size 5000

Worldengine - a world generator (v. 0.19.0)
-----------------------
 operation              : ancient_map generation
 resize factor          : 1
 world file             : worldofethos.world
 sea color              : brown
 draw biome             : True
 draw rivers            : True
 draw mountains         : True
 draw land outer border : False

starting (it could take a few minutes) ...
Traceback (most recent call last):
  File "<string>", line 619, in <module>
  File "<string>", line 586, in main
  File "<string>", line 143, in operation_ancient_map
  File "/media/workspace/WorldEngine/worldengine/worldengine/draw.py", line 804, in draw_ancientmap_on_file
  File "/media/workspace/WorldEngine/worldengine/worldengine/drawing_functions.py", line 833, in draw_ancientmap
  File "/media/workspace/WorldEngine/worldengine/worldengine/drawing_functions.py", line 215, in _draw_temperate_forest1
  File "/media/workspace/WorldEngine/worldengine/worldengine/image_io.py", line 224, in __setitem__
IndexError: index 5000 is out of bounds for axis 1 with size 5000
main returned -1

While most my errors have be from just running out of memory while generating worlds, this happened after I was able to successfully generate a world using

worldengine --not-fade-borders world -r -s 51293 -n worldofethos -q 80 -x 5000 -y 5000

But trying to generate an ancient_map caused the above error. This is on Debian 8.5 jessie, using a build from the release page.

CPU: Intel Xeon CPU E3-1245 v3 @ 3.8GHz 32171MB of Ram x86_64 Linux 3.16.0-4-amd64

if that should matter.

(note I was able to generate a world and a map with the same argument, except with 4,000 instead of 5,000)

Mindwerks / worldengine

IndexError: index 5000 is out of bounds for axis 1 with size 5000 #233