Handle case where 2 matches in the same tree are found

app/finders/group_children_finder.rb

@@ -52,7 +52,7 @@ class GroupChildrenFinder
   end
 
   def subgroups_matching_filter
-    all_subgroups.search(params[:filter]).include(:parent)
+    all_subgroups.search(params[:filter])
   end
 
   def subgroups
@@ -64,7 +64,7 @@ class GroupChildrenFinder
              else
                base_groups
              end
-    groups = groups.includes(:route).includes(:children)
+    groups = groups
     groups.sort(params[:sort])
   end
 
@@ -75,7 +75,6 @@ class GroupChildrenFinder
   def projects_matching_filter
     ProjectsFinder.new(current_user: current_user).execute
       .search(params[:filter])
-      .include(:namespace)
       .where(namespace: all_subgroups)
   end
 
@@ -87,7 +86,6 @@ class GroupChildrenFinder
                else
                  base_projects
                end
-    projects = projects.includes(:route)
     projects.sort(params[:sort])
   end
 end

app/models/concerns/group_hierarchy.rb

@@ -62,7 +62,12 @@ module GroupHierarchy
     # If both of them are hashes, we can deep_merge with the same logic
     elsif first_child.is_a?(Hash) && second_child.is_a?(Hash)
       first_child.deep_merge(second_child) { |key, first, second| merge_values(first, second) }
-    # One of them is a root node, we just need to put them next to eachother in an array
+    # If only one of them is a hash, we can check if the other child is already
+    # included, we don't need to do anything when it is.
+    elsif first_child.is_a?(Hash) && first_child.keys.include?(second_child)
+      first_child
+    elsif second_child.is_a?(Hash) && second_child.keys.include?(first_child)
+      second_child
     else
       Array.wrap(first_child) + Array.wrap(second_child)
     end

spec/models/concerns/group_hierarchy_spec.rb

@@ -124,6 +124,12 @@ describe GroupHierarchy, :nested_groups do
 
         expect(described_class.merge_hierarchies(elements, parent)).to eq(expected_hierarchy)
       end
+
+      it 'merges to elements in the same hierarchy' do
+        expected_hierarchy = { parent => subgroup }
+
+        expect(described_class.merge_hierarchies([parent, subgroup])).to eq(expected_hierarchy)
+      end
     end
   end
 end