[Checkins] [zopefoundation/BTrees] 2908ae: Fix __all__

[Jason Madden]

  Branch: refs/heads/issue132
  Home:   https://github.com/zopefoundation/BTrees
  Commit: 2908ae7425db2e864b6d7c37801b900de32a55e6
      https://github.com/zopefoundation/BTrees/commit/2908ae7425db2e864b6d7c37801b900de32a55e6
  Author: Jason Madden <jamadden at gmail.com>
  Date:   2020-03-21 (Sat, 21 Mar 2020)

  Changed paths:
    M .gitignore
    M .travis.yml
    M BTrees/_module_builder.py
    M BTrees/tests/common.py
    M CHANGES.rst
    M setup.py

  Log Message:
  -----------
  Fix __all__

Add unit tests for it and run the documentation tests that originaly caught the problem in CI.

Fixes #132