pygame.error: File is not a Windows BMP file

i got the following error with the recent version from github:

 jojoo@soy% python mario_level_1.py
 Traceback (most recent call last):
   File "mario_level_1.py", line 10, in <module>
     from data.main import main
   File "/private/tmp/Mario-Level-1/data/main.py", line 3, in <module>
     from . import setup,tools
   File "/private/tmp/Mario-Level-1/data/setup.py", line 25, in <module>
     GFX   = tools.load_all_gfx(os.path.join("resources","graphics"))
   File "/private/tmp/Mario-Level-1/data/tools.py", line 115, in load_all_gfx
     img = pg.image.load(os.path.join(directory, pic))
 pygame.error: File is not a Windows BMP file