The call to PyBuffer_IsContiguous() (see patch) is redundant:

PyBUF_WRITABLE is a flag that can be added to any buffer request.
The real request here is (PyBUF_SIMPLE|PyBUF_WRITABLE), which is
equal to PyBUF_WRITABLE since PyBUF_SIMPLE==0.

PyBUF_SIMPLE implies C-contiguous with format 'B'.


Perhaps the check was added for broken buffer providers, but I
think at some point we should assume correct providers.