Comment 4 for bug 1906547

Reviewed: https://review.opendev.org/c/starlingx/tools/+/786141
Committed: https://opendev.org/starlingx/tools/commit/82cb355f7f4a18ca1375709747ca5923f374ec26
Submitter: "Zuul (22348)"
Branch: f/centos8

commit 82cb355f7f4a18ca1375709747ca5923f374ec26
Author: Scott Little <email address hidden>
Date: Wed Dec 2 12:08:27 2020 -0500

    Fix selection of release specific mock prototype

    Commit https://review.opendev.org/c/starlingx/root/+/762700
    was intended to include the code to select the release specific
    mock config prototype.

        e.g. mock.cfg.centos7.proto

    As delivered, it would always select the default.

        e.g. mock.cfg.proto

    Other improvements:
    - remove some trailing whitespace
    - improved cleanup of temorary directories

    Closes-Bug: 1906547
    Signed-off-by: Scott Little <email address hidden>
    (cherry picked from commit 451b9513e4d224d47e3d4d2d543e1bc834b78794)
    Change-Id: Idd307e60c266716a0a7f3beebf0a05b4a8ad37d5