Make the darn virtualenv if specified

Change-Id: I492beff1211edbd8269bce50c843bfb31d2fda7a
diff --git a/src/test/setup/prerequisites.sh b/src/test/setup/prerequisites.sh
index cd6bcd1..1cbea42 100755
--- a/src/test/setup/prerequisites.sh
+++ b/src/test/setup/prerequisites.sh
@@ -73,6 +73,7 @@
 if [ $venv -eq 1 ]; then
     echo "Making a virtual cord-tester pip installation environment"
     mkdir -p $setup_path/venv
+    virtualenv $setup_path/venv
     echo "Installing cord-tester pip packages on the virtual environment"
     $setup_path/venv/bin/pip install -r $setup_path/requirements.txt
 else