revlog: fix type confusion with sidedata_comp_len (issue6580) The format string uses "i" (int) for sidedata_comp_len, so we shouldn't be passing a pointer to Py_ssize_t to PyArg_ParseTuple. On 64-bit big-endian, this would result in python only writing to the upper 32 bits, and things go downhill from there. Differential Revision: https://phab.mercurial-scm.org/D11334