All pages result in 503 from Varnish temporarally.

After we deploy code to our "dev" Acquia environment we have a hook that flushes varnish for the domain there. Immediately after a domain purge all pages on the site come back with a 503 error. The error goes away after a refresh, but it was a pain for Acquia to debug because it wasn't producing any kind of error log. This error apparently is the result of the page not being entirely gzipped.

To resolve this temporarally we disabled the features of devel that would output in the footer as part of devel_shutdown_real.

Offending code:

function devel_shutdown_real() {
 ...
    if ($output) {
      // TODO: gzip this text if we are sending a gzip page.
      // See drupal_page_header().
      // For some reason, this is not actually printing for cached pages even
      // though it gets executed and $output looks good.
      print $output;
    }
 ...
}

Temporary solution:

drush <site-alias> dev_timer 0
drush <site-alias> devel_memory 0