Show all pipelines from all merge_request_diffs:

app/models/merge_request.rb

@@ -745,10 +745,18 @@ class MergeRequest < ActiveRecord::Base
   end
 
   def all_pipelines
-    @all_pipelines ||=
-      if diff_head_sha && source_project
-        source_project.pipelines.order(id: :desc).where(sha: commits_sha, ref: source_branch)
+    return unless source_project
+
+    @all_pipelines ||= begin
+      if persisted?
+        sha = merge_request_diffs.flat_map(&:commits_sha).uniq
+      else
+        sha = diff_head_sha
       end
+
+      source_project.pipelines.order(id: :desc).
+        where(sha: sha, ref: source_branch)
+    end
   end
 
   def merge_commit

app/models/merge_request_diff.rb

@@ -117,6 +117,14 @@ class MergeRequestDiff < ActiveRecord::Base
     project.commit(head_commit_sha)
   end
 
+  def commits_sha
+    if @commits
+      commits.map(&:sha)
+    else
+      st_commits.map { |commit| commit[:id] }
+    end
+  end
+
   def diff_refs
     return unless start_commit_sha || base_commit_sha
 

spec/models/merge_request_spec.rb

@@ -495,15 +495,34 @@ describe MergeRequest, models: true do
   end
 
   describe '#all_pipelines' do
-    let!(:pipelines) do
-      subject.merge_request_diff.commits.map do |commit|
-        create(:ci_empty_pipeline, project: subject.source_project, sha: commit.id, ref: subject.source_branch)
+    shared_examples 'returning pipelines with proper ordering' do
+      let!(:pipelines) do
+        subject.merge_request_diffs.flat_map do |diff|
+          diff.commits.map do |commit|
+            create(:ci_empty_pipeline,
+                   project: subject.source_project,
+                   sha: commit.id,
+                   ref: subject.source_branch)
+          end
+        end
+      end
+
+      it 'returns all pipelines' do
+        expect(subject.all_pipelines).not_to be_empty
+        expect(subject.all_pipelines).to eq(pipelines.reverse)
       end
     end
 
-    it 'returns a pipelines from source projects with proper ordering' do
-      expect(subject.all_pipelines).not_to be_empty
-      expect(subject.all_pipelines).to eq(pipelines.reverse)
+    context 'with single merge_request_diffs' do
+      it_behaves_like 'returning pipelines with proper ordering'
+    end
+
+    context 'with multiple irrelevant merge_request_diffs' do
+      before do
+        subject.update(target_branch: 'markdown')
+      end
+
+      it_behaves_like 'returning pipelines with proper ordering'
     end
   end