Wrong connection string when using PostgreSQL

[Julien Danjou]

using enable_service postgresql generates this kind of connection strings:

connection = postgresql+pymysql://root:foobar@127.0.0.1/keystone?client_encoding=utf8

probably because MySQL is still loaded and SQLALCHEMY_DATABASE_DRIVER is set to something.

Adding disable_mysql fixes that.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/221248

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/221248
Committed: https://git.openstack.org/cgit/openstack-dev/devstack/commit/?id=0eec4f86c1ac607bfbdf1ec19561b3bbdb56cf4f
Submitter: Jenkins
Branch: master

commit 0eec4f86c1ac607bfbdf1ec19561b3bbdb56cf4f
Author: Julien Danjou <email address hidden>
Date: Tue Sep 8 10:45:06 2015 +0000

    database: fix PostgreSQL connection string

    If all databases drivers are loaded, MySQL SQLAlchemy driver
    overrides all the other one that might not have set one.
    This patches fixes that.

    Change-Id: If6d8d08e5b7b7c48ca012677b536d71058def6fd
    Closes-Bug: #1493304

[OpenStack Infra (hudson-openstack)]

Related fix proposed to branch: master
Review: https://review.openstack.org/254060

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/254060
Committed: https://git.openstack.org/cgit/openstack-dev/devstack/commit/?id=239a9788b3f73495efbdf586425a83d714be4412
Submitter: Jenkins
Branch: master

commit 239a9788b3f73495efbdf586425a83d714be4412
Author: YAMAMOTO Takashi <email address hidden>
Date: Mon Dec 7 17:09:59 2015 +0900

    Remove a stale comment about SQLALCHEMY_DATABASE_DRIVER

    SQLALCHEMY_DATABASE_DRIVER is no longer used
    after If6d8d08e5b7b7c48ca012677b536d71058def6fd .

    Also, remove mysql connector packages from the install list.

    Closes-Bug: #1523377
    Related-Bug: #1493304
    Change-Id: I5ecbc3b0bac989faa5c46d3c2866558a505414d8