changes environment.last_deployment to a try expression so it does not fail if…

app/views/projects/builds/show.html.haml

@@ -40,13 +40,13 @@
               This build is the most recent deployment to #{environment_link_for_build(@build.project, @build)}.
             - else
               This build is an out-of-date deployment to #{environment_link_for_build(@build.project, @build)}.
-              - if environment.last_deployment
+              - if environment.try(:last_deployment)
                 View the most recent deployment #{deployment_link(environment.last_deployment)}.
           - elsif @build.complete? && !@build.success?
             The deployment of this build to #{environment_link_for_build(@build.project, @build)} did not succeed.
           - else
             This build is creating a deployment to #{environment_link_for_build(@build.project, @build)}
-            - if environment.last_deployment
+            - if environment.try(:last_deployment)
               and will overwrite the
               = link_to 'latest deployment', deployment_link(environment.last_deployment)