'buffer' does not have the buffer interface

[tsumi]

Hi,
on python 2.7.3, running MapWorlds.sh i get this error:

minetest@srv-nya:~/.minetest/mods/mapit$ ./MapWorlds.sh 
/home/minetest/.minetest/worlds/world
world
Result image (w=592 h=672) will be written to /home/minetest/.minetest/mods/mapit/textures/world.png
Error at (-23,3,-28): 'buffer' does not have the buffer interface
Traceback (most recent call last):
  File "minetestmapper-numpy.py", line 626, in generate_map_info
    f = db.get(ps)
  File "minetestmapper-numpy.py", line 436, in get
    return BytesIO(r[0])
TypeError: 'buffer' does not have the buffer interface
Block data: Traceback (most recent call last):
  File "minetestmapper-numpy.py", line 1086, in <module>
    main()
  File "minetestmapper-numpy.py", line 1081, in main
    world.generate_map_info(str_to_uid)
  File "minetestmapper-numpy.py", line 788, in generate_map_info
    for c in r[0]:
NameError: global name 'r' is not defined