ipython/ipython — pull request #4738 by minrk (2013-12-23 20:17:05+00:00)
Title: don't inject help into user_ns

because it's in builtins. I presume this was for old Pythons, but it doesn't seem necessary for ≥ 2.7.

Prompted because the injection fails on 3.4, causing the warning:

WARNING: help() not available - check site.py

but help actually works just fine.