mktmpenv --help makes current venv temporary

[hazelnutfox]

Story:
I had a venv activated and decided to do mktmpenv to test some dependencies. Now that I want to switch back, I noticed the original is not there...

Step to reproduce:

1. mkvirtualenv test_gh - deactivates and activates normally
2. mktmpenv --help - this cds into it and makes the README.tmpenv file
3. deactivate - removes the venv (I did mktmpenv properly and it automatically deactivated the previous one without me noticing)

Related: mktmpenv shows mkvirtualenv's help + "This is a temporary environment. It will be deleted when you run 'deactivate'.". (I didn't notice it at first/thought it's just what command appends and didn't think it's about my current env)

mktmpenv sees mkvirtualenv --help as successful call (because it is!) and continues with making currently active venv as temporary... Solution would be to find --help/-h early and just call mkvirtualenv --help and not continue.