Fix broken specs. #3945

app/controllers/projects/merge_requests_controller.rb

@@ -104,7 +104,8 @@ class Projects::MergeRequestsController < Projects::ApplicationController
     @commit = @merge_request.last_commit
     @first_commit = @merge_request.first_commit
     @diffs = @merge_request.compare_diffs
-    @diff_refs = [@merge_request.target_sha, @merge_request.source_sha]
+    # We need to use #source_branch because #source_sha requires an existent MergeRequestDiff object.
+    @diff_refs = [@merge_request.target_sha, @merge_request.source_branch]
 
     @ci_commit = @merge_request.ci_commit
     @statuses = @ci_commit.statuses if @ci_commit

lib/gitlab/diff/highlight.rb

@@ -73,7 +73,7 @@ module Gitlab
 
           # Only update text if line is found. This will prevent
           # issues with submodules given the line only exists in diff content.
-          line.text = highlighted_line.gsub!(/\A\s/, line_prefix) if line
+          line.text = highlighted_line.gsub!(/\A\s/, line_prefix) if highlighted_line
         end
 
         @lines