parsers: fix Py2.4 argument parsing issue Since fa53d66b45a8, we were getting this strange message with Py2.4: TypeError: argument 1 must be impossible<bad format char>, not int ..because we were using the 'n' type specifier introduced in 2.5. It turns out that offset is actually a revision number index, which ought to be an int anyway. So we store it in an int, use the 'i' specifier, rely on Py_ParseTuple for range checking, and rename it to avoid type confusion.