test_migrations: fails when func.now()

[Isaku Yamahata]

The followings column, test_models_sync() fails with mysql.
It seems like it's due to mysql way of server_default.

model
    created_at = sa.Column(
        sa.DateTime().with_variant(
            sqlite.DATETIME(truncate_microseconds=True), 'sqlite'),
        server_default=sa.func.now())

alembic
        sa.Column('created_at', sa.DateTime, server_default=sa.func.now()),

msg
  [ ( 'modify_default',
      None,
      'opendaylightjournal',
      'created_at',
      { 'existing_nullable': True,
        'existing_type': DATETIME()},
      DefaultClause(<sqlalchemy.sql.elements.TextClause object at 0x7f652188ce50>, for_update=False),
      DefaultClause(<sqlalchemy.sql.functions.now at 0x7f6522411050; now>, for_update=False))],

output of debugger session (with format modification)
(Pdb) diff
[[('modify_default',
    None,
   'opendaylight_maintenance',
   'lock_updated',
   {'existing_nullable': False, 'existing_type': TIMESTAMP()},
   DefaultClause(<sqlalchemy.sql.elements.TextClause object at 0x7f6e02362810>, for_update=False),
   DefaultClause(<sqlalchemy.sql.functions.now at 0x7f6e03057a90; now>, for_update=False))],
   [('modify_default',
      None,
     'opendaylightjournal',
     'created_at',
     {'existing_nullable': True, 'existing_type': DATETIME()},
     DefaultClause(<sqlalchemy.sql.elements.TextClause object at 0x7f6e024d1fd0>, for_update=False),
     DefaultClause(<sqlalchemy.sql.functions.now at 0x7f6e030570d0; now>, for_update=False))],
   [('modify_default',
      None,
     'opendaylightjournal',
     'last_retried',
    {'existing_nullable': True, 'existing_type': TIMESTAMP()},
      DefaultClause(<sqlalchemy.sql.elements.TextClause object at 0x7f6e024600d0>, for_update=False),
      DefaultClause(<sqlalchemy.sql.functions.now at 0x7f6e03057250; now>, for_update=False))]]
(Pdb) diff[0][0][5]
DefaultClause(<sqlalchemy.sql.elements.TextClause object at 0x7f6e02362810>, for_update=False)
(Pdb) diff[0][0][5].arg
<sqlalchemy.sql.elements.TextClause object at 0x7f6e02362810>
(Pdb) diff[0][0][5].arg.text
u'CURRENT_TIMESTAMP'
(Pdb) diff[0][0][5].reflected
True
(Pdb) diff[0][0][6]
DefaultClause(<sqlalchemy.sql.functions.now at 0x7f6e03057a90; now>, for_update=False)
(Pdb) diff[0][0][6].arg
<sqlalchemy.sql.functions.now at 0x7f6e03057a90; now>
(Pdb) diff[0][0][6].reflected
False

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/390017
Committed: https://git.openstack.org/cgit/openstack/networking-odl/commit/?id=10167f5bb8b403e3377d4f12f6f23ef1a0bc24f2
Submitter: Jenkins
Branch: master

commit 10167f5bb8b403e3377d4f12f6f23ef1a0bc24f2
Author: Isaku Yamahata <email address hidden>
Date: Fri Oct 21 22:27:33 2016 -0700

    add test_migrations test

    Change-Id: Iae1ca021aa2eedef1b06fa84f58c5f407b9b5c81
    Related-bug: #1635915

[Isaku Yamahata (yamahata)]

for networking-odl, it's triaged as low.