db_api iscsi_target_create_safe() constraint violation

[Yuriy Zveryanskyy]

iscsi_target_create_safe() allows create multiple identical "target_num", "host" pair,
violate UniqueConstraint("target_num", "host") in model.
Reproduced in my test.
https://review.openstack.org/31640

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/31640

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/31640
Committed: http://github.com/openstack/cinder/commit/34e649e065099626d0b1b8ccc1f0e9da1b64fa1d
Submitter: Jenkins
Branch: master

commit 34e649e065099626d0b1b8ccc1f0e9da1b64fa1d
Author: Yuriy Zveryanskyy <email address hidden>
Date: Tue Jun 4 15:56:54 2013 +0300

    Add missing tests for iscsi_* methods

    There was no tests in test_db_api for iscsi_*
    methods.

    Bug 1187367 found.

    blueprint db-api-tests

    Change-Id: Ia554e6030307a0c4f0510ab74fe0881ee160f743

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/111760
Committed: https://git.openstack.org/cgit/openstack/cinder/commit/?id=331071a3e2f1ee6783e6a908789af40835818eed
Submitter: Jenkins
Branch: master

commit 331071a3e2f1ee6783e6a908789af40835818eed
Author: Ivan Kolodyazhny <email address hidden>
Date: Mon Aug 4 18:16:10 2014 +0300

    Catch DBDuplicateEntry instead of IntegrityError

    'iscsi_target_create_safe' method didn't catch DB exceptions
    correct.

    Need to catch both db_exc.DBError and db_exc.DBDuplicateEntry
    due to current oslo.db limitations: it doesn't handle correct
    DBDuplicateEntry with different SQLite versions

    Related-Bug: #1187367

    Change-Id: Ie412ecabd3cbcac301340c82b4275adb7a7206c3