Comment 4 for bug 1733207

Reviewed: https://review.openstack.org/521381
Committed: https://git.openstack.org/cgit/openstack/horizon/commit/?id=faaa4aed8cd5547647e9a080239cd4f1f9fd4697
Submitter: Zuul
Branch: master

commit faaa4aed8cd5547647e9a080239cd4f1f9fd4697
Author: Akihiro Motoki <email address hidden>
Date: Sun Nov 19 17:27:44 2017 +0000

    Avoid sending error message twice in BatchAction

    BatchAction.handle() displays an aggregate error message
    if an exception is returned from individual action() method.
    If we don't need a detail error message, try/except is unnecessary.

    Note that a fix for a case where a detail error message is needed
    will be covered in the subsequent patches.

    Change-Id: I8037355b12e0756c6add5c5b9ba05a430155dfe5
    Partial-Bug: #1733207