CodeNarc is skipped on Travis CI when pom.xml was modified

[php-coder]

Found during debugging #1478: when we modify pom.xml we expect that CodeNarc will be triggered but it doesn't:

INFO: Range of the commits to be checked: 1025e577e7a2...e9eb6238c9fa
INFO: List of the files modified by this commits range:
 infra/vagrant/provisioning/roles/mystamps-app/templates/application-prod.properties
 pom.xml
 src/main/java/ru/mystamps/web/feature/site/SiteConfig.java
 src/main/java/ru/mystamps/web/support/mailgun/ApiMailgunEmailSendingStrategy.java
 src/main/java/ru/mystamps/web/support/spring/boot/ThymeleafViewResolverInitializingBean.java
 src/main/java/ru/mystamps/web/support/spring/security/SecurityConfig.java
 src/main/resources/application-postgres.properties
 src/main/resources/application-test.properties
 src/main/resources/application-travis.properties
 src/main/resources/application.properties
 src/main/scripts/ci/check-build-and-verify.sh
 src/test/resources/logback-test.xml
INFO: Some checks could be skipped

* Run CheckStyle... SUCCESS
* Run PMD... SUCCESS
* Check license headers... SUCCESS
* Check sorting of pom.xml... SKIP
* Run bootlint... SKIP
* Run robot framework lint... SKIP
* Run shellcheck... SUCCESS
* Run JavaScript unit tests... SKIP
* Run html5validator... SKIP
* Run maven-enforcer-plugin... SKIP
* Run unit tests... SUCCESS
* Run CodeNarc... SKIP
* Run SpotBugs... SUCCESS
* Run Ansible Lint... SKIP
* Run integration tests... SUCCESS
* Run danger... SKIP

See a full log: https://travis-ci.org/github/php-coder/mystamps/jobs/750656752

[php-coder]

BTW I couldn't reproduce it locally but it's reproducible on Travis CI (when I restarted that job).

[php-coder]

I'm trying to debug it on Travis as I have a theory that it might be environment-specific. Here is a useful link: https://docs.travis-ci.com/user/running-build-in-debug-mode/

[php-coder]

There is another build that modifies pom.xml as well but CodeNarc hasn't been skipped -- https://travis-ci.com/github/php-coder/mystamps/jobs/464383612