Error clearing Drupal caches when Varnish is missing from settings.php

Since this patch went into the dev branch, I get the following error message when trying to clear cache's on my development environment (where I don't have Varnish setup).

Exception: Invalid or missing cache bin specified: <em class="placeholder">external_varnish_page</em> in DrupalDatabaseCache->clear() (line 516 of /path/to/mysite/includes/cache.inc).

My setup is that I have different settings.php files for production/staging/development environments.
I have only been including the necessary Varnish config on my production and staging settings.php, and development would work gracefully without it. But now that we have a varnish_flush_caches(), we're getting trouble.