[Checkins] [zopefoundation/ZEO] 184750: Work around a beneficial race

[GitHub]

  Branch: refs/heads/avoid-future-timeouts
  Home:   https://github.com/zopefoundation/ZEO
  Commit: 184750c9bf7e9eb56a64f0dd36f42c6a77f37aa3
      https://github.com/zopefoundation/ZEO/commit/184750c9bf7e9eb56a64f0dd36f42c6a77f37aa3
  Author: Jim Fulton <jim at zope.com>
  Date:   2016-10-26 (Wed, 26 Oct 2016)

  Changed paths:
    M src/ZEO/tests/drop_cache_rather_than_verify.txt

  Log Message:
  -----------
  Work around a beneficial race

When data are loaded, we notify waiting code before updating the cache.

This can confuse white-box tests that make assertions about the client
cache after a load, because the cache change may or may not have been
made yet.