readline module missing in python:2.7-slim

[crepererum]

Python 2.7.10 (default, Jun  9 2015, 21:06:35) 
[GCC 4.9.2] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import readline
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ImportError: No module named readline

See https://docs.python.org/2/library/readline.html

Someone could argue that the python-slim only contains software relevant for servers, but sometimes it would be very helpful to get some debug interfaces working. For example iPython works way better when the readline module is available.

[tianon]

readline is a normal module (just like curses), so I'm definitely +1 to this working (and have added it to the tests in docker-library/official-images#832)