Issue #3467938 by yas: drupal/cloud:8.x-dev

Closes #3467938

.tugboat/config.yml

@@ -186,7 +186,7 @@ services:
         set -eux
 
         # Delete and re-check out this branch in case this is built from a Base Preview.
-        git checkout 7.x && git branch -D "${TUGBOAT_REPO_ID}" && git checkout -b "${TUGBOAT_REPO_ID}" || true
+        git checkout 8.x && git branch -D "${TUGBOAT_REPO_ID}" && git checkout -b "${TUGBOAT_REPO_ID}" || true
         export COMPOSER_MEMORY_LIMIT=-1
         cd "${DRUPAL_COMPOSER_ROOT}"
         composer install --optimize-autoloader