[gnome-runtime-images/alatiera/scheduled-stable-rebuilds] Avoid rebuilding base images unless needed

[Jordan Petridis <jpetridis src gnome org>]

commit 91b5ab2de6a52cb29ade35d50cc31db8ed363291
Author: Jordan Petridis <jpetridis gnome org>
Date:   Thu Apr 23 12:26:24 2020 +0300

    Avoid rebuilding base images unless needed

 .gitlab-ci.yml | 12 ++++++++++++
 1 file changed, 12 insertions(+)
---
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 1605b7b..5a8cabb 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -44,6 +44,8 @@ default:
           END
         - podman run --rm ${DOCKERIMAGE} flatpak list --columns=application,branch,arch,active,size
         - buildah inspect --format "{{.FromImageID}}" ${DOCKERIMAGE}
+    rules:
+      - when: 'manual'
 
 base:
     stage: base
@@ -51,6 +53,11 @@ base:
     variables:
         DOCKERIMAGE: ${CI_REGISTRY_IMAGE}/base
         DOCKERFILE: base
+    rules:
+      - changes:
+        - 'base'
+        when: 'always'
+      - when: 'manual'
 
 flat-manager-client:
     stage: base
@@ -58,6 +65,11 @@ flat-manager-client:
     variables:
         DOCKERIMAGE: ${CI_REGISTRY_IMAGE}/flat-manager-client
         DOCKERFILE: flat-manager-client/Dockerfile
+    rules:
+      - changes:
+        - 'flat-manager-client/Dockerfile'
+        when: 'always'
+      - when: 'manual'
 
 
 # Expects ${BRANCH} and ${FD_BRANCH} variables which are the gnome branch and the freedesktop-sdk