Remove py26 oldest tests (certbot#4856)

* Remove py26 oldest tests.

The only systems where we support Python 2.6 use certbot-auto so the oldest
supported versions of our dependencies are never used when using supported
installation methods. Let's remove this unnecessary and slow test.

* Make tox.ini happy

* Remove py26-oldest from Travis

.travis.yml

@@ -33,13 +33,6 @@ matrix:
         - sudo cat /var/log/mysql/error.log
         - ps aux | grep mysql
       services: docker
-    - python: "2.6"
-      env: TOXENV=py26-oldest BOULDER_INTEGRATION=1
-      sudo: required
-      after_failure:
-        - sudo cat /var/log/mysql/error.log
-        - ps aux | grep mysql
-      services: docker
     - python: "2.7"
       env: TOXENV=py27_install BOULDER_INTEGRATION=1
       sudo: required

tox.ini

@@ -63,9 +63,20 @@ commands =
     {[base]install_and_test} {[base]py26_packages}
     python tests/lock_test.py
 
-[testenv:py26-oldest]
+[testenv]
 commands =
     {[testenv:py26]commands}
+    {[base]install_and_test} {[base]non_py26_packages}
+setenv =
+    PYTHONPATH = {toxinidir}
+    PYTHONHASHSEED = 0
+
+[testenv:py27-oldest]
+commands =
+    {[testenv]commands}
+setenv =
+    {[testenv]setenv}
+    CERTBOT_NO_PIN=1
 # cffi<=1.7 is required for oldest tests due to
 # https://bitbucket.org/cffi/cffi/commits/18cdf37d6b2691301a15b0e54f49757ebd4ed0f2?at=default
 # requests<=2.11.1 required for oldest tests due to
@@ -78,20 +89,6 @@ deps =
     requests<=2.11.1
     zope.component==4.0.2
     zope.interface==4.0.5
-setenv =
-    CERTBOT_NO_PIN=1
-
-[testenv]
-commands =
-    {[testenv:py26]commands}
-    {[base]install_and_test} {[base]non_py26_packages}
-setenv =
-    PYTHONPATH = {toxinidir}
-    PYTHONHASHSEED = 0
-    py27-oldest: {[testenv:py26-oldest]setenv}
-# https://testrun.org/tox/latest/example/basic.html#special-handling-of-pythonhas
-deps =
-    py27-oldest: {[testenv:py26-oldest]deps}
 
 [testenv:py27_install]
 basepython = python2.7