Currently 2to3 converts `operator.isCallable(obj)` to `hasattr(obj, '__call__')`. This looks cumbersome, and can be deceived by instance attribute __call__. The more correct way is to use `isinstance(obj, collections.abc.Callable)`. Starting from Python 3.2 it can use the callable() builtin.

I would convert this to `callable()` -- the conversion to collections.abc.Callable is more verbose and requires an extra import (that can be slow).

New changeset a489599793f9b00ddc2c68e2ce3bce9cbb2c09a2 by Éric Araujo (Dong-hee Na) in branch 'master':
bpo-32046: Update 2to3 when converts operator.isCallable(obj). (#4417)
https://github.com/python/cpython/commit/a489599793f9b00ddc2c68e2ce3bce9cbb2c09a2

Merged in master, I suppose stable branches should be left alone?

@serhiy.storchaka
If we don't have plans with backporting patches than we can close this issue.

> I suppose stable branches should be left alone?

We do backport lib2to3 PRs to maintenance branches, but since this is already in 3.7 and 3.6 is four months away from being in security-fix-only mode, I think we can close this as 'fixed' now.