Can't run install.sh within a virtualenv

[kdmukai]

Running ./install.sh within a virtualenv I get the following:

ERROR: Can not perform a '--user' install. User site-packages are not visible in this virtualenv.

Removing the --user flag resolves the issue in my virtualenv. Not submitting a pull request as this is more dependent on individual setups. But maybe add a note in the docs?

[stefanzarembinski]

Thank you for your remark: it is reasonable. However, you know, almost nobody reads documentation. Therefore, I ask you for a pool request: please make a try-cath trick (with a message explaining the case), automatizing your solution.

I do not use any virtualenv, hence, I am asking you...