build,meta: don't fail Travis for commit message

PR-URL: #23739
Fixes: #23737
Refs: #22452
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: Yuta Hiroto <hello@hiroppy.me>
Reviewed-By: Vladimir de Turckheim <vlad2t@hotmail.com>

.travis.yml

@@ -12,7 +12,7 @@ matrix:
         - make lint
         # Lint the first commit in the PR.
         - if [ "${TRAVIS_PULL_REQUEST}" != "false" ]; then
-            bash tools/lint-pr-commit-message.sh ${TRAVIS_PULL_REQUEST};
+            bash tools/lint-pr-commit-message.sh ${TRAVIS_PULL_REQUEST} || true;
           fi
     - name: "Test Suite"
       addons: