Put requirements repo in a venv.

This is to prevent any possible contamination of test results from its
presence.

Change-Id: I5a929854745650cc6a182ffc4d15c50caabdd727
diff --git a/inc/python b/inc/python
index 3d329b5..e3c5e61 100644
--- a/inc/python
+++ b/inc/python
@@ -219,15 +219,15 @@
         if [[ "$REQUIREMENTS_MODE" == "soft" ]]; then
             if is_in_projects_txt $project_dir; then
                 (cd $REQUIREMENTS_DIR; \
-                    python update.py $project_dir)
+                    ./.venv/bin/python update.py $project_dir)
             else
                 # soft update projects not found in requirements project.txt
                 (cd $REQUIREMENTS_DIR; \
-                    python update.py -s $project_dir)
+                    ./.venv/bin/python update.py -s $project_dir)
             fi
         else
             (cd $REQUIREMENTS_DIR; \
-                python update.py $project_dir)
+                ./.venv/bin/python update.py $project_dir)
         fi
     fi