Use local_assigns

app/views/projects/deployments/_actions.haml

@@ -14,7 +14,7 @@
                   = icon("play")
                   %span= action.name.humanize
 
-    - if defined?(allow_rollback) && allow_rollback
+    - if local_assigns.fetch(:allow_rollback, false)
       = link_to [:retry, @project.namespace.becomes(Namespace), @project, deployment.deployable], method: :post, class: 'btn btn-build' do
         - if deployment.last?
           Retry