Close merge request if open without source project

app/controllers/projects/merge_requests_controller.rb

@@ -417,8 +417,10 @@ class Projects::MergeRequestsController < Projects::ApplicationController
 
   def validates_merge_request
     # If source project was removed and merge request for some reason
-    # wasn't close (Ex. mr from fork to origin)
-    return invalid_mr if !@merge_request.source_project && @merge_request.open?
+    # wasn't close (Ex. mr from fork to origin) merge request will be closed
+    if !@merge_request.source_project && @merge_request.open?
+      @merge_request.close
+    end
 
     # Show git not found page
     # if there is no saved commits between source & target branch

spec/views/projects/merge_requests/show.html.haml_spec.rb

@@ -41,4 +41,17 @@ describe 'projects/merge_requests/show.html.haml' do
       expect(rendered).to have_css('a', visible: false, text: 'Close')
     end
   end
+
+  context 'when the merge request is open' do
+    it 'closes open merge request' do
+      closed_merge_request.update_attributes(state: 'open')
+      fork_project.destroy
+
+      render
+
+      expect(closed_merge_request.reload.state).to eq('closed')
+      expect(rendered).to have_css('a', visible: false, text: 'Reopen')
+      expect(rendered).to have_css('a', visible: false, text: 'Close')
+    end
+  end
 end