Added python version in prompt for current active virtualenv

[DhiaTN]

Now if you set the flag BULLETTRAIN_VIRTUALENV_PYTHON_VERSION=true, current python version will be displayed in prompt segment. Colors and prefix can also be customized. 🐍

[ghost]

Awesome! Well Done :+1:

[vadviktor]

@DhiaTN Why do you duplicate an already existing feature? Virtualenv is doing just this.

Edit: I think I got what you want to achieve here. You can name the virtualenvs so they won't give you away with the version of the Python they use. Sorry, I always name them having the hint of the Python version in them.

Suggestion: since Python and virtualenv are very much related and we don't separate Ruby from it's gemsets, not Nodejs from it's NVM part, please find a way to merge it with the currently available virtualenv segment. Better, if you merge the virtualenv into the Python segment and make it optional to display the Python version in it. Now that would be awesome and clean.