Why does it install `pip` into the generated virtualenv? about catkin_virtualenv

[BoyanH]

This is the default functionality of Python's venv module, as described in the docs. I believe the main reason for this is to further decouple the virtual environment from the rest of your system. There might be other technical reasons which I yet don't understand, such as it perhaps being difficult to enforce pip to work on the active venv in a platform-agnostic way. I was also curious about this, so I posted Why is pip installed in virtual environments by default? on Stackoverflow.

[dimaqq]

Looks like the consensus on stackoverflow is that having pip installed into the virtualenv by default is kinda standard.

This lease two possibilities:

1. either use the special flag to no install pip into venv, or
2. let pip get installed, but also install openssl/crypto/etc so that pip actually works