Stop kong/run_tests.sh from building venv each run

Change-Id: I17e077891471e4b5e2c0372b1d2adf735f4df3ca
diff --git a/kong/run_tests.sh b/kong/run_tests.sh
index a7d7f63..96c2406 100755
--- a/kong/run_tests.sh
+++ b/kong/run_tests.sh
@@ -68,7 +68,7 @@
             echo "Cleaning virtualenv..."
             rm -rf ${venv}
         fi
-        if [ -e ${venv} ]; then
+        if [ -e "../${venv}" ]; then
             wrapper="${with_venv}"
         else
             if [ $always_venv -eq 1 ]; then