Only init submodules where needed

.gitlab-ci.yml

 image: docker:latest
 
-variables:
-  GIT_SUBMODULE_STRATEGY: recursive
-
 services:
   - docker:dind
 
@@ -109,6 +106,8 @@ build-debian-jessie-build-dev:
 # Debian WP.org Plugin deploy builds
 build-debian-wp-org-deploy-build-master:
   stage: deploy
+  variables:
+    GIT_SUBMODULE_STRATEGY: recursive
   script:
     - docker build --pull -t "$CI_REGISTRY_IMAGE/debian:wp-org-deploy" ./debian/wp-org-deploy/context
     - docker push "$CI_REGISTRY_IMAGE/debian:wp-org-deploy"
@@ -118,6 +117,8 @@ build-debian-wp-org-deploy-build-master:
 
 build-debian-wp-org-deploy-build-dev:
   stage: deploy
+  variables:
+    GIT_SUBMODULE_STRATEGY: recursive
   script:
     - docker build --pull -t "$CI_REGISTRY_IMAGE/debian:wp-org-deploy-dev" ./debian/wp-org-deploy/context
     - docker push "$CI_REGISTRY_IMAGE/debian:wp-org-deploy-dev"