Desperate measures: Introduce singlequotes to check if things are still not working

deploy/venv.sls

@@ -42,8 +42,8 @@ deploy_{{ project_name }}_venv:
         LANG: en_US.UTF-8
         LC_CTYPE: en_US.UTF-8
         LC_ALL: en_US.UTF-8
-        PIP_TRUSTED_HOST: apt-proxy.it.hs-hannover.de
-        PIP_INDEX_URL: http://apt-proxy.it.hs-hannover.de:3141/root/pypi/+simple/
+        PIP_TRUSTED_HOST: 'apt-proxy.it.hs-hannover.de'
+        PIP_INDEX_URL: 'http://apt-proxy.it.hs-hannover.de:3141/root/pypi/+simple/'
     - require:
         - file: deploy_venv_directory
         - pkg: deploy_venv_pkgs