[Checkins] [zopefoundation/ZODB] 16dc5b: Allow serial to be returned as late as tpc_finish

[GitHub]

  Branch: refs/heads/tpc_finish
  Home:   https://github.com/zopefoundation/ZODB
  Commit: 16dc5b0b3f4d81bed7d0334e944bbe1f5798d5ca
      https://github.com/zopefoundation/ZODB/commit/16dc5b0b3f4d81bed7d0334e944bbe1f5798d5ca
  Author: Vincent Pelletier <vincent at nexedi.com>
  Date:   2016-06-17 (Fri, 17 Jun 2016)

  Changed paths:
    M src/ZODB/Connection.py
    M src/ZODB/interfaces.py
    M src/ZODB/tests/BasicStorage.py
    M src/ZODB/tests/MTStorage.py
    M src/ZODB/tests/RevisionStorage.py
    M src/ZODB/tests/StorageTestBase.py
    M src/ZODB/tests/TransactionalUndoStorage.py
    M src/ZODB/tests/testDemoStorage.py

  Log Message:
  -----------
  Allow serial to be returned as late as tpc_finish

This makes possible for storage to allocate serial inside tpc_finish,
removing the requirement to serialise 2PC's second phase phase (tpc_vote
to tpc_finish/tpc_abort).

Co-Authored-By: Julien Muchembled <jm at nexedi.com>