Inline Method refactoring is allowed in abstract methods.

[jonhnanthan]

Abstract methods do not have an implementation in the class where they are declared; their implementation is expected to be provided by concrete subclasses.
It would be nice if Rope emitted a warning.

Steps to reproduce the behavior:

1. Code before refactoring:

from abc import abstractmethod


class Base:

    @abstractmethod
    def tag(self, text, tokenize=True):
        return

2. Apply the Inline Method refactoring to Base.tag().