BufFileWrite across MAX_PHYSICAL_FILESIZE boundary

Just noticed buffile.c:292 doesn't look quite right where
BufFileDumpBuffer calls FileWrite:    bytestowrite = FileWrite(thisfile, file->buffer, bytestowrite);
It looks as though it would write the same data each time the
loop is iterated.  Would this be better?    bytestowrite = FileWrite(thisfile, file->buffer + wpos, bytestowrite);