REF: graceful degradation refactoring of tox tests

Author: pavlov99

tox.ini

@@ -1,13 +1,13 @@
 [tox]
-envlist = py26, py27, py33, py34, py35, py36, py37, py38, pypy, pypy3, pycodestyle, cov
+envlist = py{26, 27, 33, 34, 35, 36, 37, 38}, pypy, pypy3, pycodestyle, cov
 
 [testenv]
 commands = pytest
 setenv = DJANGO_SETTINGS_MODULE=jsonrpc.tests.test_backend_django.settings
 deps =
     pytest==5.2.2
-    Django==1.11
-    Flask==0.12.2
+    Django==2.2.7
+    Flask==1.1.1
 
 # Python 2.6 configuration. Latest Django support is 1.6
 [testenv:py26]
@@ -24,18 +24,33 @@ deps =
 # https://www.djangoproject.com/weblog/2015/jun/25/roadmap/
 [testenv:py27]
 deps =
-    {[testenv]deps}
+    pytest==4.0.2
+    attrs==19.1.0
     mock==2.0.0
+    Django==1.11
+    Flask==0.12.2
 
-[testenv:py38]
+[testenv:py33]
 deps =
-    {[testenv]deps}
-    Django==2.2.7
+    pytest==4.0.2
+    attrs==19.1.0
+    Django==1.11
+    Flask==0.12.2
+
+[testenv:py34]
+deps =
+    pytest==4.0.2
+    attrs==19.1.0
+    Django==1.11
+    Flask==0.12.2
 
 [testenv:pypy]
 deps =
-    {[testenv]deps}
+    pytest==4.0.2
+    attrs==19.1.0
     mock==2.0.0
+    Django==1.11
+    Flask==0.12.2
 
 [testenv:pycodestyle]
 deps = pycodestyle