Test program:

import sys
sys.setrecursionlimit(20)
def f(): return f()
f()

F:\Python\mypy>python tem.py
Traceback (most recent call last):
  File "tem.py", line 4, in <module>
    f()
  File "tem.py", line 3, in f
    def f(): return f()
...
RecursionError: maximum recursion depth exceeded

In 2.7.11, the error is caught and the user process restarted.

======================= RESTART: F:\Python\mypy\tem.py =======================

=============================== RESTART: Shell ===============================
>>> 

In 3.5.1, the user process hangs, ^C does not work, and a restart explicitly requested either with Shell => Restart or running another program.

This behavior is either peculiar to this test case, or a regression, as I remember getting proper RecursionError tracebacks in the past.