vagrant: Skip the shell virtualenv warning on provision.

Vagrantfile

@@ -100,6 +100,11 @@ $provision_script = <<SCRIPT
 set -x
 set -e
 set -o pipefail
+
+# Code should go here, rather than tools/provision, only if it is
+# something that we don't want to happen when running provision in a
+# development environment not using Vagrant.
+
 # If the host is running SELinux remount the /sys/fs/selinux directory as read only,
 # needed for apt-get to work.
 if [ -d "/sys/fs/selinux" ]; then
@@ -111,6 +116,10 @@ if ! grep -q 'LC_ALL=en_US.UTF-8' /etc/default/locale; then
     echo "LC_ALL=en_US.UTF-8" | sudo tee -a /etc/default/locale
 fi
 
+# Set an environment variable, so that we won't print the virtualenv
+# shell warning (it'll be wrong, since the shell is dying anyway)
+export SKIP_VENV_SHELL_WARNING=1
+
 # Provision the development environment
 ln -nsf /srv/zulip ~/zulip
 /srv/zulip/tools/provision

tools/provision

@@ -35,7 +35,7 @@ if [ $failed = 1 ]; then
     echo "* Logs are here: zulip/var/log/provision.log"
     echo -e "\033[0m"
     exit 1
-elif [ "$VIRTUAL_ENV" != "/srv/zulip-py3-venv" ] && [ -z "$TRAVIS" ]; then
+elif [ "$VIRTUAL_ENV" != "/srv/zulip-py3-venv" ] && [ -z "${TRAVIS}${SKIP_VENV_SHELL_WARNING}" ]; then
     echo -e "\033[0;31m"
     echo "WARNING: This shell does not have the Python 3 virtualenv activated."
     echo "Zulip commands will fail."