I'm gonna fix this now.  (I'm cleaning up some old issues I filed on the bug tracker this morning.)

For 3.4, I'm just removing the PyObject *kwargs for those three functions that don't actually accept keyword arguments (METH_VARARGS) and aren't passed that parameter.  That's a bug plain and simple, it's relying on undefined behavior, and it's better that we fix it.

For 3.5. I'm adding a call to _PyArg_NoKeywords() to pysqlite_connection_call.  Previously it simply ignored any/all keyword arguments; now it will complain if it is passed any.  We don't need a deprecation cycle for that.