While the docu on https://www.zulip.org/server.html says:
```
cd /root/zulip
./scripts/setup/install
```
This script downloads the `python-django-guardian_1.3-1~zulip4_all.deb` file to current working dir (`/root/zulip` if you follow the docu), but tries to install it from /root/.
This fails obviously. So i changed the download location to /tmp/.
We don't use apache in the main app -- only for the SSO situation --
this code was just copied from our own install script. And it caused
problems at CUSTOMER13 because they installed Apache in preparation for
the SSO integration, but restarting it failed.
(imported from commit 3f2961574134847c836e8b69736f60d9f8790201)