Comment 5 for bug 1859642

Reviewed: https://review.opendev.org/702947
Committed: https://git.openstack.org/cgit/starlingx/tools/commit/?id=7b095f365e33a6d68d524501cd953eb04df312b1
Submitter: Zuul
Branch: r/stx.3.0

commit 7b095f365e33a6d68d524501cd953eb04df312b1
Author: Don Penney <email address hidden>
Date: Tue Jan 14 11:20:50 2020 -0500

    Constrain more-itertools for build failure

    A recent update to the more-itertools python module causes a failure
    in the STX_BUILD_container_setup CENGN build job. This module dropped
    python-2.7 support after its 5.0.0 release. The newest update causes a
    failure due to code that does not work with 2.7.

    This commit adds a builder-constraints.txt file that the Dockerfile
    passes to the pip install command to constrain module versions during
    setup of the build container, allowing us to constrain the
    more-itertools version to 5.0.0, the last version to officially
    support python 2.7.

    Change-Id: I3432c204ecd7c4ddedd8a7dea14216d4ec31e0aa
    Closes-Bug: 1859642
    Signed-off-by: Don Penney <email address hidden>
    (cherry picked from commit 12c3dc47720bc8d011a746faf42b824caac8faa6)