bind(self=xxx) fails

[rbtcollins]

I have a method like so:

class F:
def f(a, self):
pass

signature(partial(F.f, None)).bind(self=10)

fails, due to receiving self too many times.

The function bind() can't be defined with self as its own parameter - it conflicts with binds that pass self in. Instead it needs to take _args, *_kwargs, and pull self out of args[0].

I'll throw up a patch in alittle, for now (in mock), I'm monkeypatching to fix it.