[Checkins] [zopefoundation/ZODB] b3c251: TransactionalUndo releases storages it opens.

[Jason Madden]

  Branch: refs/heads/issue268
  Home:   https://github.com/zopefoundation/ZODB
  Commit: b3c2514b6195d2f54aad67ed620ca82a8aa1add1
      https://github.com/zopefoundation/ZODB/commit/b3c2514b6195d2f54aad67ed620ca82a8aa1add1
  Author: Jason Madden <jamadden at gmail.com>
  Date:   2019-09-20 (Fri, 20 Sep 2019)

  Changed paths:
    M CHANGES.rst
    M src/ZODB/DB.py
    M src/ZODB/tests/testDB.py

  Log Message:
  -----------
  TransactionalUndo releases storages it opens.

Fixes #268.