DEBUG Try installing source to see if we get the missing files

.travis.yml

@@ -1,6 +1,6 @@
 language: php
 
-dist: trusty
+dist: xenial
 
 addons:
   firefox: "31.0"
@@ -34,7 +34,7 @@ before_script:
   - composer validate
   - composer require --no-update silverstripe/recipe-cms:"$RECIPE_VERSION"
   - if [[ $DB == PGSQL ]]; then composer require --no-update silverstripe/postgresql:2.1.x-dev; fi
-  - composer install --prefer-dist --no-interaction --no-progress --no-suggest --optimize-autoloader --verbose --profile
+  - composer install --prefer-source --no-interaction --no-progress --no-suggest --optimize-autoloader --verbose --profile
 
   # Start behat services
   - if [[ $BEHAT_TEST ]]; then echo 'SS_BASE_URL=http://localhost:8080/' >> .env; fi