vjahia2wp: don't even run "make" if the venv exists
vjahia2wp: don't even run "make" if the venv exists

This makes no difference timing-wise, but it eliminates some log noise.

epfl-idevelop/jahia2wp,epfl-idevelop/jahia2wp,epfl-idevelop/jahia2wp,epfl-idevelop/jahia2wp