Add disco-stein bundle to gate tests

The bundle disco-stein was in the dev bundles because
a bug with the Python 3.7 syntax prevented the success of
the deployment of HA clusters. This bug is fixed, we can
reintegrate disco-stein in the gate bundles.

Other small additions:
- removing sitepackages in tox.ini to avoid test env pollution
- skip_missing_interpreters in tox.ini set to False to avoid false
positives by skipping missing interpreters.

LP Related-Bug: #1823718

Change-Id: Ie4199aba3261f78f3592301bfd1e3d0be9cc7444

.gitignore

@@ -3,3 +3,4 @@
 *__pycache__*
 *.pyc
 build
+.idea

src/tests/tests.yaml

@@ -1,5 +1,6 @@
 charm_name: octavia
 gate_bundles:
+- disco-stein
 - bionic-stein-ha
 - bionic-rocky-ha
 - disco-stein

src/tox.ini

@@ -1,12 +1,16 @@
 [tox]
 envlist = pep8
 skipsdist = True
+# NOTE(beisner): Avoid build/test env pollution by not enabling sitepackages.
+sitepackages = False
+# NOTE(beisner): Avoid false positives by not skipping missing interpreters.
+skip_missing_interpreters = False
 
 [testenv]
 setenv = VIRTUAL_ENV={envdir}
          PYTHONHASHSEED=0
 whitelist_externals = juju
-passenv = HOME TERM CS_API_* OS_* AMULET_*
+passenv = HOME TERM CS_API_* OS_*
 deps = -r{toxinidir}/test-requirements.txt
 install_command =
   pip install {opts} {packages}

tox.ini

@@ -3,7 +3,11 @@
 # within individual charm repos.
 [tox]
 skipsdist = True
-envlist = pep8,py37
+envlist = pep8,py3
+# NOTE(beisner): Avoid build/test env pollution by not enabling sitepackages.
+sitepackages = False
+# NOTE(beisner): Avoid false positives by not skipping missing interpreters.
+skip_missing_interpreters = False
 
 [testenv]
 setenv = VIRTUAL_ENV={envdir}