parser.py cannot be run from different directory

[rvernica]

The parser.py script cannot be run from a different directory as the script cannot find the preprocessor.pijnu file:

> python PATH_TO_MEDIAWIKI-PARSER_DIR/parser.py 
Traceback (most recent call last):
  File "/home/vernica/usr/src/mediawiki-parser/parser.py", line 8, in <module>
    preprocessorGrammar = file("preprocessor.pijnu").read()
IOError: [Errno 2] No such file or directory: 'preprocessor.pijnu'
Exit 1