Follow-up: Move linters dependencies to tox.ini

After commit 89e2fad8ef856f0e3651e4ea5784d28bc9aeb229,
pep8/bandit/bashate tox envs have different dependencies than
the default tox env. If tox envs with different dependencies share
some common envdir, tox env will be recreated every time a different
tox env is specified. (For example, "tox -e cover" after "tox -e pep8"
recreates the tox env.)

To address it, this commit introduces a new common envdir for linters
(envdir = {toxworkdir}/lint). It also moves deependencies of bashate
and bandit envs to pep8 env to ensure these three tox envs have the
same dependencies.

Cleanups are also made in test-requirements and lower-constraints.
* astroid and isort can be dropped from test-requirements.txt
  as pylint has proper version cappings for astroid and isort.
  (These cappings are available in pylint 2.5 and later.)
* reno is a document dependency, so it is unnecessary in test-requirements.
* reno, astroid and isort are dropped from lower-constraints
  as they are not installed in lower-constraints tests.

Change-Id: Iaa3168764d050875e3d08784aee2dfba809e53be

lower-constraints.txt

@@ -31,7 +31,6 @@ greenlet==0.4.14
 httplib2==0.9.1
 imagesize==0.7.1
 iso8601==0.1.11
-isort==4.3.21
 Jinja2==2.10
 jmespath==0.9.0
 jsonpatch==1.16
@@ -109,7 +108,6 @@ python-novaclient==9.1.0
 python-subunit==1.0.0
 pytz==2013.6
 PyYAML==5.3.1
-reno==3.1.0
 repoze.lru==0.7
 requests==2.14.2
 requestsexceptions==1.2.0

test-requirements.txt

@@ -10,9 +10,6 @@ testscenarios>=0.4 # Apache-2.0/BSD
 WebTest>=2.0.27 # MIT
 oslotest>=3.2.0 # Apache-2.0
 stestr>=1.0.0 # Apache-2.0
-reno>=3.1.0 # Apache-2.0
 ddt>=1.0.1 # MIT
-astroid==2.4.0 # LGPLv2.1
-isort==4.3.21 # MIT
 # Needed to run DB commands in virtualenvs
 PyMySQL>=0.7.6 # MIT License

tox.ini

@@ -94,11 +94,11 @@ deps = -r{toxinidir}/doc/requirements.txt
 commands = sphinx-build -a -E -W -d releasenotes/build/doctrees -b html releasenotes/source releasenotes/build/html
 
 [testenv:pep8]
-envdir = {toxworkdir}/shared
+envdir = {toxworkdir}/lint
 deps =
   {[testenv]deps}
-  {[testenv:bashate]deps}
-  {[testenv:bandit]deps}
+  bashate>=0.5.1 # Apache-2.0
+  bandit!=1.6.0,>=1.1.0 # Apache-2.0
   flake8-import-order==0.18.1 # LGPLv3
   pylint==2.5.3 # GPLv2
 commands=
@@ -203,20 +203,17 @@ extension =
 import_exceptions = neutron._i18n
 
 [testenv:bandit]
-envdir = {toxworkdir}/shared
+envdir = {toxworkdir}/lint
+deps = {[testenv:pep8]deps}
 # B104: Possible binding to all interfaces
 # B303: prohibit list calls: md5, sha1
 # B311: Standard pseudo-random generators are not suitable for security/cryptographic purpose
 # B604: any_other_function_with_shell_equals_true
-deps =
-  bandit!=1.6.0,>=1.1.0 # Apache-2.0
-  -r{toxinidir}/test-requirements.txt
 commands = bandit -r neutron -x tests -n5 -s B104,B303,B311,B604
 
 [testenv:bashate]
-envdir = {toxworkdir}/shared
-deps =
-  bashate>=0.5.1 # Apache-2.0
+envdir = {toxworkdir}/lint
+deps = {[testenv:pep8]deps}
 commands = bash -c "find {toxinidir}             \
          -not \( -type d -name .tox\* -prune \)  \
          -not \( -type d -name .venv\* -prune \) \