[Checkins] [zopefoundation/ZODB] ef66eb: Import warnings on demand.

[GitHub]

  Branch: refs/heads/issue158
  Home:   https://github.com/zopefoundation/ZODB
  Commit: ef66eb304df3babce1fc770cfc295cc355e41d0f
      https://github.com/zopefoundation/ZODB/commit/ef66eb304df3babce1fc770cfc295cc355e41d0f
  Author: Jason Madden <jamadden at gmail.com>
  Date:   2017-04-11 (Tue, 11 Apr 2017)

  Changed paths:
    M CHANGES.rst
    M src/ZODB/blob.py

  Log Message:
  -----------
  Import warnings on demand.

Fixes #158.