round included:
* Revert round to its 2.6 behavior (half away from 0).
* Because round, floor, and ceil always return float again, it's no
longer necessary to have them delegate to __xxx___, so I've ripped
that out of their implementations and the Real ABC. This also helps
in implementing types that work in both 2.6 and 3.0: you return int
from the __xxx__ methods, and let it get enabled by the version
upgrade.
* Make pow(-1, .5) raise a ValueError again.
9871d8fe22