Increase python version coverage for tests. (#24762)

* Improve ansible-test inventory handling.
* Fix python 3 re-raise of exception from thread.
* Fix python 3 encoding for windows-integration.
* Run network tests on multiple python versions.
* Run windows tests on multiple python versions.
* Support Shippable delegation using --tox.
* Skip vyos_command on python 3 tests until fixed.
* Add python 3 filtering to local and tox.
* Fix tests to support back to back runs.
* Temporarily test networking with python 2.7 only.

Running the tests back to back causes intermittent test failures
which need to be addressed before we can test multiple versions
in a single test run.

test/runner/lib/delegation.py

@@ -35,6 +35,8 @@ from lib.util import (
     ApplicationError,
     EnvironmentConfig,
     run_command,
+    common_environment,
+    pass_vars,
 )
 
 from lib.docker_util import (
@@ -129,7 +131,18 @@ def delegate_tox(args, exclude, require):
             if args.coverage and not args.coverage_label:
                 cmd += ['--coverage-label', 'tox-%s' % version]
 
-        run_command(args, tox + cmd)
+        env = common_environment()
+
+        # temporary solution to permit ansible-test delegated to tox to provision remote resources
+        optional = (
+            'SHIPPABLE',
+            'SHIPPABLE_BUILD_ID',
+            'SHIPPABLE_JOB_NUMBER',
+        )
+
+        env.update(pass_vars(required=[], optional=optional))
+
+        run_command(args, tox + cmd, env=env)
 
 
 def delegate_docker(args, exclude, require):