Okay, types corrected, most comments taken into account.
%b is right out, %a is still suffering scrutiny.
The arguments seem to boil down to:
We don't need it.
vs
Somebody might, and it's better than having them inappropriately add a
__bytes__ method if we don't have it.
"We don't need it" doesn't really need any further explanation.
Does anybody have any examples where %a could be useful? Considering
the work-arounds are either wrong or painful, it wouldn't take much to
sway me towards keeping it, but at the moment it seems to be a YAGNI,
plus we could always add it later if it turns out to be useful. (For
that matter, we could implement the main portion of the PEP now, and
maybe a %a use-case will show up before 3.5 is released and we could add
it then.)
So, any last thoughts about %a?