Maybe stages will help?

.gitlab-ci.yml

@@ -1,16 +1,18 @@
 # Composer stores all downloaded packages in the vendor/ directory.
 # Do not use the following if the vendor/ directory is commited to
 # your git repository.
-cache:
-  paths:
-  - vendor/
 
 services:
     - redis:latest
 
+stages:
+    - test
+
+test:
     test:7:
+        stage: test
         before_script:
-      - bash build/docker_install.sh > /dev/null
+          - sh build/docker_install.sh > /dev/null
           - curl -sS https://getcomposer.org/installer | php
           - php composer.phar install --no-dev
         image: php:7-alpine
@@ -18,8 +20,9 @@ test:7:
           - phpunit -c build --coverage-text --colors=never
 
     test:7.1:
+        stage: test
         before_script:
-      - bash build/docker_install.sh > /dev/null
+          - sh build/docker_install.sh > /dev/null
           - curl -sS https://getcomposer.org/installer | php
           - php composer.phar install --no-dev
         image: php:7.1-alpine
@@ -27,6 +30,7 @@ test:7.1:
           - phpunit -c build --coverage-text --colors=never
 
     test:hhvm:
+        stage: test
         allow_failure: true
         before_script:
           - /usr/local/bin/composer self-update