I'm not sure this belongs in the same PR. Quicker access to underlying estimators in a Pipeline has been recently considered in #2561, #2562, #2568. I don't entirely object to the fitted models appearing as pipeline attributes, but it should be explicit, like `pipe.clf__coef_`, not order-determined `pipe.coef_`. If nothing else, your solution would be a problem for backwards-compatibility: a dev may add a new attribute to some class that someone has used in a pipeline, and suddenly it would be retrieving the wrong one.

As to other attributes, like methods and parameters, I think these should not be available in this sort of delegation (for example, parameters should be settable if they are getable).

Finally, you should use `__getattr__` rather than `__getattribute__` as the former only fires if the name isn't found by the default attribute resolution procedure (i.e. you can remove the `try-except`.