Vim's advance word broken in python, how do I fix this?

Vim works fine for all other languages, but word detection seems wonky in python. For example, in the following snippet, with the cursor on the 'h' in shutil, I would expect prssing the w key to advance me to the period, instead I get moved to the "'" in front of export.

shutil.copytree(os.path.join('export', 'app'), os.path.join('export', 'pacakge'))

Any idea what could cause this? How can I d开发者_运维知识库etect the cause? How can I fix it?

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Look to see what the option "iskeyword" is set to. Chances are the Python syntax file is changing it. Normally it's set to @,48-57,_,192-255.