Avoid passenv=* with tox (#2784)

Author: ssbarnea

.ansible.cfg

@@ -0,0 +1 @@
+# Used for testing to avoid using one from outside repository

tox.ini

@@ -19,8 +19,16 @@ isolated_build = True
 install_command =
     python -c 'import subprocess, sys; pip_inst_cmd = sys.executable, "-m", "pip", "install"; subprocess.check_call(pip_inst_cmd + ("pip<19.1", )); subprocess.check_call(pip_inst_cmd + tuple(sys.argv[1:]))' {opts} {packages}
 usedevelop = True
-passenv = *
+# do not put * in passenv as it may break builds do to reduced isolation
+passenv =
+    CI
+    DOCKER_*
+    GITHUB_*
+    HOME
+    PODMAN_*
+    TERM
 setenv =
+    ANSIBLE_CONFIG={toxinidir}/dev/null
     ANSIBLE_CALLABLE_WHITELIST={env:ANSIBLE_CALLABLE_WHITELIST:timer,profile_roles}
     ANSIBLE_DISPLAY_FAILED_STDERR=1
     ANSIBLE_VERBOSITY=1