prepare-integration.sh: support alt VIRTUALENV_DIR

scripts/github/prepare-integration.sh

@@ -6,9 +6,13 @@ if [ "$(whoami)" != 'root' ]; then
     exit 2
 fi
 
+# ./virtualenv is the Makefile managed dir.
+# The workflow should set this to use a pants exported or other venv instead.
+VIRTUALENV_DIR="${VIRTUALENV_DIR:-./virtualenv}"
+
 # Activate the virtualenv created during make requirements phase
-# shellcheck disable=SC1091
-source ./virtualenv/bin/activate
+# shellcheck disable=SC1090,SC1091
+source "${VIRTUALENV_DIR}/bin/activate"
 
 echo "Used config for the tests"
 echo ""
@@ -22,7 +26,9 @@ cat conf/st2.ci.conf || true
 echo ""
 
 # install st2 client
-python ./st2client/setup.py develop
+if [ ! -x "${VIRTUALENV_DIR}/bin/st2" ] || ! st2 --version >/dev/null 2>&1; then
+    python ./st2client/setup.py develop
+fi
 st2 --version
 
 # Clean up old st2 log files
@@ -56,7 +62,7 @@ chmod 777 logs/*
 
 # root needs to access write some lock files when creating virtualenvs
 # o=other; X=only set execute bit if user execute bit is set (eg on dirs)
-chmod -R o+rwX ./virtualenv/
+chmod -R o+rwX "${VIRTUALENV_DIR}/"
 # newer virtualenv versions are putting lock files under ~/.local
 # as this script runs with sudo, HOME is actually the CI user's home
 chmod -R o+rwX "${HOME}/.local/share/virtualenv"