Backport changes from EE squashsquash

Backport changes from the EE-only squash implementation, which would
otherwise conflict when merge CE into EE.

<https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/1024>

1 files changed, 11 insertions, 3 deletions

diff --git a/spec/models/repository_spec.rb b/spec/models/repository_spec.rb
index 829b69093c9..775bdc91d70 100644
--- a/spec/models/repository_spec.rb
+++ b/spec/models/repository_spec.rb
@@ -15,7 +15,12 @@ describe Repository, models: true do
 
   let(:merge_commit) do
     merge_request = create(:merge_request, source_branch: 'feature', target_branch: 'master', source_project: project)
-    merge_commit_id = repository.merge(user, merge_request, commit_options)
+
+    merge_commit_id = repository.merge(user,
+                                       merge_request.diff_head_sha,
+                                       merge_request,
+                                       commit_options)
+
     repository.commit(merge_commit_id)
   end
 
@@ -1009,8 +1014,11 @@ describe Repository, models: true do
 
     it 'sets the `in_progress_merge_commit_sha` flag for the given merge request' do
       merge_request = create(:merge_request, source_branch: 'feature', target_branch: 'master', source_project: project)
-      merge_commit_id = repository.merge(user, merge_request, commit_options)
-      repository.commit(merge_commit_id)
+
+      merge_commit_id = repository.merge(user,
+                                         merge_request.diff_head_sha,
+                                         merge_request,
+                                         commit_options)
 
       expect(merge_request.in_progress_merge_commit_sha).to eq(merge_commit_id)
     end