Confusing comment in tidbitmap.c

The following comment above #define PAGES_PER_CHUNK in tibbitmap.c appears
to be incorrect:

"But we
* also want PAGES_PER_CHUNK to be a power of 2 to avoid expensive integer
* remainder operations. So, define it like this:"

I don't quite follow this as it does nothing of the kind.
Check tbm_page_is_lossy() where we do: bitno = pageno % PAGES_PER_CHUNK;

Or am I missing something about the compiler optimizing that to: bitno =
pageno & 255; ?

Regards

David Rowley