Graham: thanks for pointing that out; I completely forgot we already 
*had* the migration discussion on the Web-SIG!  It just slipped my 
mind because I didn't have any 3.0 work on the horizon.

Dmitry: A question about the new patch.  Are bytearray and memoryview 
objects in 3.0 really the same as bytestrings?  It seems to me that 
allowing mutable bytes objects is a mistake from a bug-finding 
standpoint, even if it could be a win from a performance 
standpoint.  I think it might be better to be more restrictive to 
start out, and then let people lobby for supporting other types, 
rather than the other way around, where we'll never get to narrow the 
list.  Apart from that, the patch looks pretty good.  Thank you!