build-iso failure due to missing repodata

[Scott Little]

Brief Description
-----------------
Build-iso started failing due to the lack of repodata in $MY_REPO/centos-repo/rt/Binary/ . The problem was traced back to generate-centos-repo.sh and an unintended modification of the dest_dir global variable. The unintended modification was due to the new function copy_with_backup failing to use 'local' on it's internal variables.

Severity
--------
Critical

Steps to Reproduce
------------------
Flock layer build ...
generate-centos-repo.sh
...
build-iso

Expected Behavior
------------------
1) generate-centos-repo.sh produces a repodata under $MY_REPO/centos-repo/rt/Binary/repodata
2) build-iso passes

Actual Behavior
----------------
1) generate-centos-repo.sh fails to create a repodata under $MY_REPO/centos-repo/rt/Binary/repodata
2) build-iso failes

Reproducibility
---------------
100%

System Configuration
--------------------
N/A

Branch/Pull Time/Commit
-----------------------
Oct 26 2020
stx-tools: 44cda9d881f4d38b0362dd93eae46bda62869fc0

Last Pass
---------
Oct 25 2020

Timestamp/Logs
--------------
03:26:58 failure: repodata/repomd.xml from StxCentos7Distro-rt: [Errno 256] No more mirrors to try.
03:26:58 file:///localdisk/designer/jenkins/master-flock/cgcs-root/centos-repo/rt/Binary/repodata/repomd.xml: [Errno 14] curl#37 - "Couldn't open file /localdisk/designer/jenkins/master-flock/cgcs-root/centos-repo/rt/Binary/repodata/repomd.xml"
...
03:27:10 Could not resolve packages: rt-setup
03:27:10 Error -- could not install all explicitly listed packages

Test Activity
-------------
build

Workaround
----------

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/760175
Committed: https://git.openstack.org/cgit/starlingx/tools/commit/?id=33648c9b34880a1184ca48982518a16ecdf16105
Submitter: Zuul
Branch: master

commit 33648c9b34880a1184ca48982518a16ecdf16105
Author: Scott Little <email address hidden>
Date: Wed Oct 28 12:00:34 2020 -0400

    build-iso failure due to missing repodata

    Build-iso started failing due to the lack of
    repodata in $MY_REPO/centos-repo/rt/Binary/ .

    The problem was traced back to generate-centos-repo.sh
    and an unintended modification of the dest_dir global
    variable. The unintended modification was due to
    the new function copy_with_backup failing to use
    'local' on it's internal variables.

    Closes-bug: 1901920
    Change-Id: If1c3928518552327af9e01a77b287849a1e3981b
    Signed-off-by: Scott Little <email address hidden>

[Ghada Khalil (gkhalil)]

stx.5.0 / critical - consistent build failure