Use ensure to revert @disable_ancestry_callbacks

[daniloisr]

Hello, I ran into a problem because I need the return of the block passed to without_ancestry_callbacks:

# always returns false instead of the result of inner_block
def some_method
  without_ancestry_callbacks { inner_block } 
end

So I think that ensure is a good fit here.

Note, this is probably a breaking change (although I think no one is relying on the result of without_ancestry_callbacks right now), so should we create a new method for this?

[kbrock]

LGTM. just running the tests.

ping me if I do not merge this soon.

[kbrock]

kicking