Makes tempest sendmail failure easier to track

This task can fail with various errors and this change enables us
to spot its failure with a single LogStash query.

In order to avoid false positive string match when bash is using verbose
more we encoded the W char in the source, so a string match would happen
only when printed and not on the source code.

Change-Id: Icbb7f71aba2e9d2a4cf4e4c07f953fe3613e6707
Partial-Bug: 1806495

roles/validate-tempest/tasks/tempest-results.yml

@@ -68,7 +68,8 @@
           "{{ lookup('env', 'JOB_NAME')|default('Periodic job', true) }}"
           --file "{{ working_dir }}/{{ tempest_log_file }}"
           --log-url "{{ tempestmail_log_server }}"
-          --skip-file "{{ working_dir }}/tempestmail/tempest_skip_{{ release }}.yml"
+          --skip-file "{{ working_dir }}/tempestmail/tempest_skip_{{ release }}.yml" ||
+          { ERR=$?; echo -e "\0127ARNING: Send tempest results by mail failed with code $ERR"; exit $ERR; }
       args:
         chdir: "{{ working_dir }}/tempestmail"
       ignore_errors: true