SITE_URL is used for other things, so I believe it has to be accurate per environment. It's currently set in the settings/local.py on each env to be accurate (https://www-dev.allizom.org, https://www.allizom.org, etc.). So setting it in settings/base.py will have no affect when deployed. We have robots.txt setup to disallow indexing for every environment except production. Why is that not good?