Remove dependency on the "mock" package on Python 3

Author: mnaberez

tox.ini

@@ -4,30 +4,37 @@ envlist =
 
 [testenv]
 deps =
-    attrs < 21.1.0  # see https://github.com/python-attrs/attrs/pull/608
-    pytest
+    attrs < 21.1.0    # see https://github.com/python-attrs/attrs/pull/608
     pexpect == 4.7.0  # see https://github.com/Supervisor/supervisor/issues/1327
-    mock >= 0.5.0
+    pytest
 passenv = END_TO_END
 commands =
     pytest --capture=no {posargs}
 
-[testenv:py27-configparser]
-;see https://github.com/Supervisor/supervisor/issues/1230
+[testenv:py27]
 basepython = python2.7
 deps =
     {[testenv]deps}
-    configparser
+    mock >= 0.5.0
 passenv = {[testenv]passenv}
 commands = {[testenv]commands}
 
+[testenv:py27-configparser]
+;see https://github.com/Supervisor/supervisor/issues/1230
+basepython = python2.7
+deps =
+    {[testenv:py27]deps}
+    configparser
+passenv = {[testenv:py27]passenv}
+commands = {[testenv:py27]commands}
+
 [testenv:cover]
 basepython = python2.7
-commands =
-    pytest --capture=no --cov=supervisor --cov-report=term-missing --cov-report=xml {posargs}
 deps =
-    {[testenv]deps}
+    {[testenv:py27]deps}
     pytest-cov
+commands =
+    pytest --capture=no --cov=supervisor --cov-report=term-missing --cov-report=xml {posargs}
 
 [testenv:cover3]
 basepython = python3.8