parsers: use 'k' format for Py_BuildValue instead of 'n' because Python 2.4 'n' was introduced in Mercurial in 2b5940f64750 and broke Python 2.4 support in mysterious ways that only showed failure in test-glog.t. Py_BuildValue failed because of the unknown format and a TypeError was thrown ... but it never showed up on the Python side and it happily continued processing with wrong data. Quoting https://docs.python.org/2/c-api/arg.html : n (integer) [Py_ssize_t] Convert a Python integer or long integer to a C Py_ssize_t. New in version 2.5. k (integer) [unsigned long] Convert a Python integer or long integer to a C unsigned long without overflow checking. This will use unsigned long instead of Py_ssize_t. That is not a good solution, but good is not an option when we have to support Python 2.4.