Comment 2 for bug 1539173

Reviewed: https://review.openstack.org/326819
Committed: https://git.openstack.org/cgit/openstack/mistral/commit/?id=70adb4512f0ac0be2e8162b0038f9ddba16fca92
Submitter: Jenkins
Branch: master

commit 70adb4512f0ac0be2e8162b0038f9ddba16fca92
Author: Renat Akhmerov <email address hidden>
Date: Wed Jun 8 11:42:38 2016 +0700

    Add a test that verifies an old bug with join

    * There was a bug in stable/libery that occurred in case when we
      had a "join" task that joined multiple branches sourced from
      the same task. In this case line 302 (in the current revision)
      in direct_workflow.py caused IndexError when evaluating in_t_ex[-1]
      as described in the bug. This bug was implicitly fixed since then
      but a test for it was missing. This patch adds a test to prevent
      this bug occurrence in the future.

    Change-Id: If277989cc9149b219a9c63287290daa321a3e438
    Closes-Bug: #1539173