py3.7 async is a keyword

[Corey Bryant]

I'm working on packaging nova for rocky on ubuntu cosmic which is now at py3.7. In py3.7 "async" is a keyword, which results in issues such as:

Failed to import test module: nova.tests.unit
Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/unittest2/loader.py", line 490, in _find_test_path
    package = self._get_module_from_name(name)
  File "/usr/lib/python3/dist-packages/unittest2/loader.py", line 395, in _get_module_from_name
    __import__(name)
  File "/<<PKGBUILDDIR>>/nova/tests/unit/__init__.py", line 30, in <module>
    objects.register_all()
  File "/<<PKGBUILDDIR>>/nova/objects/__init__.py", line 28, in register_all
    __import__(\'nova.objects.aggregate\')
  File "/<<PKGBUILDDIR>>/nova/objects/aggregate.py", line 23, in <module>
    from nova.db.sqlalchemy import api as db_api
  File "/<<PKGBUILDDIR>>/nova/db/sqlalchemy/api.py", line 218
    reader_mode = get_context_manager(context).async
                                                   ^
SyntaxError: invalid syntax

[Corey Bryant (corey.bryant)]

note that this will need to be paired with oslo.db commit df6bf3401266f42271627c1e408f87c71a06cef7 "Rename enginefacade.async to enginefacade.async_".

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/584365

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/584365
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=2d532963fa2e013e16cc403f2674a4488c4170ab
Submitter: Zuul
Branch: master

commit 2d532963fa2e013e16cc403f2674a4488c4170ab
Author: Corey Bryant <email address hidden>
Date: Fri Jul 20 09:01:56 2018 -0400

    In Python3.7 async is a keyword [1]

    Change all instances of "async" to "async_"

    [1] https://docs.python.org/3/whatsnew/3.7.html

    Change-Id: I974b1177ba8313ac502910ca358cf386ef00bc02
    Closes-Bug: #1782746

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/nova 18.0.0.0rc1 release candidate.