[perf] virtualenv: install boilerplate only once
[perf] virtualenv: install boilerplate only once

Install boilerplate packages (pip, wheel, setuptools and requirements.txt) only
once, when virtualenv is created.

Signed-off-by: Markus Heiser <14dfd67dd72e7ac80c040b62bb932f1e121795cc@darmarit.de>

dalf/searx,dalf/searx,dalf/searx,dalf/searx