Site config: Don't explode if Host header is unset
Site config: Don't explode if Host header is unset

Django's Client test helper doesn't set it

codeforboston/cornerwise,codeforboston/cornerwise,codeforboston/cornerwise,cityofsomerville/citydash,cityofsomerville/citydash,cityofsomerville/citydash,cityofsomerville/cornerwise,cityofsomerville/citydash,codeforboston/cornerwise,cityofsomerville/cornerwise,cityofsomerville/cornerwise,cityofsomerville/cornerwise