Build detail Overview tab should show only most recent rebuild

[cpolcyn]

When a build is rebuilt, logs at the Build level are appended. Then when viewed on the Overview tab of the build or rebuilt detail view, all logs are shows. Rebuilds should have their own logs and the Overview tab should display logs for only the most recent rebuild, or the original build if there are no rebuilds. It's clearer to the user and consistent with how other tabs operate.