Message8780

`int.__pow__(x, y, None)` returns NotImplemented, whereas `pow(x, y, None)` gives the correct result.

Sample session:

Jython 2.7b2 (default:a5bc0032cf79+, Apr 22 2014, 21:20:17) 
[Java HotSpot(TM) 64-Bit Server VM (Oracle Corporation)] on java1.8.0_05
Type "help", "copyright", "credits" or "license" for more information.
>>> pow(10,10,None)
10000000000L
>>> int.__pow__(10,10,None)
NotImplemented
>>> (10).__pow__(10, None)
NotImplemented