gitlabci: avoid building dev version when updating the base image

.gitlab-ci.yml

@@ -47,8 +47,13 @@ build_base_image:
 build_dev_version:
   stage: build
   except:
-    - tags
-    - master
+    refs:
+      - tags
+      - master
+    changes:
+      - Dockerfile-base
+      - Pipfile
+      - Pipfile.lock
   environment: staging
   tags:
     - docker-image-build
@@ -106,6 +111,11 @@ tag_image_prod:
 ### Import image into OpenShift. Import $CI_COMMIT_TAG if present or 'latest' if not.
 import_image_dev:
   stage: import_image
+  except:
+    changes:
+      - Dockerfile\-base
+      - Pipfile
+      - Pipfile.lock
   environment: staging
   image: gitlab-registry.cern.ch/paas-tools/openshift-client:latest
   script: