Command line is not Python, try to use double quotes.
And it would be useful to write your original regex. This seemes to be a malformed command rather than a replace.py error.

2011/9/9 Kudu <kududot@gmail.com>
node:pywikipedia kudu$ python replace.py -transcludes:sometemplate
-regex 'someregex' 'somereplacement'


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