tests: Manage ANSIBLE_STRATEGY with Tox

.ci/ci_lib.py

@@ -193,8 +193,6 @@ class Fold(object):
     def __exit__(self, _1, _2, _3): pass
 
 
-os.environ.setdefault('ANSIBLE_STRATEGY',
-    os.environ.get('STRATEGY', 'mitogen_linear'))
 GIT_ROOT = os.path.abspath(os.path.join(os.path.dirname(__file__), '..'))
 # Used only when MODE=mitogen
 DISTRO = os.environ.get('DISTRO', 'debian9')

tox.ini

@@ -85,6 +85,7 @@ passenv =
     AWS_SECRET_ACCESS_KEY
     HOME
 setenv =
+    ANSIBLE_STRATEGY = mitogen_linear
     NOCOVERAGE_ERASE = 1
     NOCOVERAGE_REPORT = 1
     # Only applicable to MODE=mitogen
@@ -115,7 +116,7 @@ setenv =
     mode_ansible: MODE=ansible
     mode_debops_common: MODE=debops_common
     mode_mitogen: MODE=mitogen
-    strategy_linear: STRATEGY=linear
+    strategy_linear: ANSIBLE_STRATEGY=linear
 whitelist_externals =
     docker
     docker-credential-secretservice