* origin/issue590:
issue #590: disable distro test on vanilla
ci: Ansible 2.8 jobs aren't running against all host types.
tests: Py3.x fix.
issue #590: fix test for <2.8 Ansibles.
tests: Py3.x fix.
issue #590: actually run Ansible test.
tests: Py3.x fix.
master: sysconfig did not exist until 2.7.
tests: rearrange test modules again, they're used in multiple places
module_finder_test: mask one more difference between unit2 vs. direct start
master: fix _is_stdlib_path() failure on Ubuntu.
issue #590: add dummy package for new test.
issue #590: add FinderMethod docstrings.
issue #590: update comment to indicate the hack is permanent
issue #590: move example modules to module_finder/, fix/add tests
issue #590: refactor ModuleFinder and teach it a new special case.
issue #590: Ansible test for module_utils.distro use.
issue #590: teach importer to handle self-replacing modules