Debian: sw-manager patch-strategy show fails

[Al Bailey]

Brief Description
-----------------
Running sw-manager patch-strategy show reports a stracktrace on debian

This issue is not related to patching (which is still under construction) but is due to python3 differences.

Severity
--------
Minor

Steps to Reproduce
------------------
source /etc/platform/openrc
sw-manager patch-strategy show

Expected Behavior
------------------
Should report that no strategy is found

Actual Behavior
----------------
Reports a stack trace, and the nfv-vim-api.log shows it is failing while writing to tcp

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

System Configuration
--------------------
Debian AIO-SX

Branch/Pull Time/Commit
-----------------------
May 1, 2022

Last Pass
---------
N/A

Timestamp/Logs
--------------
2022-05-02T13:25:52.440 controller-0 VIM-API_Thread[61586] ERROR Server-side error: "can't concat str to bytes". Detail:
Traceback (most recent call last):

  File "/usr/lib/python3/dist-packages/wsmeext/pecan.py", line 84, in callfunction
    result = f(self, *args, **kwargs)

  File "/usr/lib/python3/dist-packages/nfv_vim/api/controllers/v1/orchestration/sw_update/_sw_update_strategy.py", line 485, in get_all
    vim_connection.send(rpc_request.serialize())

  File "/usr/lib/python3/dist-packages/nfv_common/tcp/_tcp_connection.py", line 128, in send
    msg += payload

TypeError: can't concat str to bytes

Test Activity
-------------
Feature Testing

Workaround
----------
None.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/c/starlingx/nfv/+/840213

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/c/starlingx/nfv/+/840213
Committed: https://opendev.org/starlingx/nfv/commit/985739f7fbb2e2961b94707cd2ea93440425ea01
Submitter: "Zuul (22348)"
Branch: master

commit 985739f7fbb2e2961b94707cd2ea93440425ea01
Author: Al Bailey <email address hidden>
Date: Mon May 2 15:24:43 2022 +0000

    Debian: Fix VIM API calls

    On python 2 struct.pack returns a string, and therefore a
    payload of type 'string' can be appended to it, before
    being converted to bytes for writing to tcp.

    On python 3 struct.pack returns bytes, and therefore a
    payload of type 'string' can not be appended to it.
    The payload needs to be converted to bytes first. The
    conversion of bytes to bytes (writing to tcp) is a no-op.

    This change has no impact on python2 code.

    Test Plan:
      PASS: "sw-manager patch-strategy show" does not generate
           exceptions in nfv-vim or nfv-vim-api logs on Debian.

    Closes-Bug: 1971171
    Signed-off-by: Al Bailey <email address hidden>
    Change-Id: Ia4fc56ca20f1e013ad1432802c4f18793ee3bb26