Failure when creating virtualenv

[BrandonTheBuilder]

virtualenv removed the flag --no-site-packages causing a failure when creating environments.

· Creating environments
·· Error running /venvs/py36/bin/python3.6 -mvirtualenv --no-site-packages -p /usr/bin/python2.7 /data/.asv/env/17eb0d1a118ba63221e952bc6a9973f3
   STDOUT -------->
   
   STDERR -------->
   usage: virtualenv [--version] [--with-traceback] [-v | -q] [--discovery {builtin}] [-p py] [--creator {builtin,cpython2-posix}] [--seeder {app-data,pip}] [--no-seed] [--activators comma_separated_list] [--clear] [--system-site-packages]
                     [--symlinks | --copies] [--download | --no-download] [--extra-search-dir d [d ...]] [--pip version] [--setuptools version] [--wheel version] [--no-pip] [--no-setuptools] [--no-wheel] [--clear-app-data] [--symlink-app-data]
                     [--prompt prompt] [-h]
                     dest
   virtualenv: error: unrecognized arguments: --no-site-packages

·· Failure creating environment for virtualenv-py2.7-pip+mock

[tylerjereddy]

I ran into this today

[rossbar]

Ran into this as well.

FWIW, until a fix is in place this can be gotten around by using a pre 20.* version of virtualenv: pip install asv virtualenv==16.7.9

[oscarbenjamin]

Apparently the --no-site-packages option has not been needed for some time. Maybe it can just be removed:
https://stackoverflow.com/a/60783839/9450991

[ilayn]

Another hit from me today. It seems to me that #905 is safe to merge.