When a tracing/profiling function is registered via 

  'PyEval_SetTrace()' or 'PyEval_SetProfile()', 

calling registered C functions should lead to calls of
the tracing function with reason 

  'PyTrace_C_CALL' and 'PyTrace_C_RETURN'.

This does not work if the function call uses keyword
arguments (test case attached) ! 

The reason seems to be that in
'Python/ceval.c:call_function ()' the macro 'C_TRACE'
is used to wrap the calling of build-in functions into
the corresponding calls of the tracing function. This
does not apply if keyword arguments are used, in that
case 'do_call ()' is called directly without being
wrapped into that macro.