IPython.core.interactiveshell:InteractiveShell.init_virtualenv

Summary

Add the current virtualenv to sys.path so the user can import modules from it. This isn't perfect: it doesn't use the Python interpreter with which the virtualenv was built, and it ignores the --no-site-packages option. A warning will appear suggesting the user installs IPython in the virtualenv, but for many cases, it probably works well enough.