zendesk/active_record_shards — pull request #4 by seancaffery (2013-08-16 02:11:38+00:00)
Title: Patch ActiveRecord 3 exists? with scopes

AcitveRecord 3 will delegate exists? to the Relation rather than
ActiveRecord::Base if it is called on a scope, meaning that
SomeModel.some_scope.exists? will run a query on the master

/cc @zendesk/quokka @osheroff @tsturge @grosser @shajith @steved555