[Checkins] [zopefoundation/ZODB] e9c749: Clean DB properties on close (#123)

[GitHub]

  Branch: refs/heads/master
  Home:   https://github.com/zopefoundation/ZODB
  Commit: e9c7492ab1fc429b65fc143879aedd50faac0b1a
      https://github.com/zopefoundation/ZODB/commit/e9c7492ab1fc429b65fc143879aedd50faac0b1a
  Author: Adam Groszer <agroszer at gmail.com>
  Date:   2017-05-17 (Wed, 17 May 2017)

  Changed paths:
    M src/ZODB/DB.py
    M src/ZODB/tests/multidb.txt
    M src/ZODB/tests/testDB.py

  Log Message:
  -----------
  Clean DB properties on close (#123)

* clean up references to DBs and Connections in pools
* Implement an explicit clear() method for clearing all the items in the pool.