Currently astroid goes into a total revamp, having a couple of development branches with partially
incompatible APIs, which means that pylint can't rely on the exact location of has_known_bases
and safe_infer until astroid reaches a new major release. With this in mind, these two
functions are backported in pylint again.
* this patch adds the basis of a new checker, 'async', which deals
with problems that can occur when working with async features added
in Python with PEP 492.
* We're also adding a new error, 'yield-inside-async-function', emitted on
Python 3.5 and upwards when the `yield` statement is found inside
a new coroutine function (PEP 492).
* Another new error is added, 'not-async-context-manager', emitted when
an async context manager block is used with an object which doesn't
support this protocol (PEP 492).
