Ben, would you be interested in making a Github pull request against the current master for your patch?  It appears there was interest in moving forward with this and it is still occurring on 3.7, although it now raises a RecursionError.

>>> d = {}
>>> d[1] = d.keys()
>>> d
{1: dict_keys([1])}
>>> d[2] = d.values()
>>> d
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
RecursionError: maximum recursion depth exceeded while getting the repr of an object