--no-cache-dir option for requirements.txt

[booo]

I'm trying to install packages with pip from a requirements.txt file and I can't install the packages in the virtualenv because pip wants to create a cache in the local home of the user that executes the pip command. The user does not have a home dir and I don't want to create one. Is there a working option to add --no-cache-dir to the pip command? I tried pip_args and pip_extra_args and both did not work :/

Thanks for your help.