I am torn on this. On one hand, it would be good to be consistent with the single-argument behaviour. But on the other hand, APIs normally accept arbitrary bytes-like objects (like memoryview) to minimise unnecessary copying, whereas this case has to make a copy to append a null terminator.

Perhaps another option is to deprecate int(byteslike) support instead, in favour of explicitly making a copy using bytes(byteslike). Similarly for float, compile, eval, exec, which also do copying thanks to Issue 24802. But PyNumber_Long() has called PyObject_AsCharBuffer() (predecessor of Python 3’s bytes-like objects) since 1.5.2 (revision 74b7213fb609). So this option would probably need wider discussion.