FIX: when advancing draft sequence remove old drafts

app/models/draft_sequence.rb

@@ -11,6 +11,7 @@ class DraftSequence < ActiveRecord::Base
     c.sequence ||= 0
     c.sequence += 1
     c.save
+    exec_sql("DELETE FROM drafts WHERE user_id = :user_id AND draft_key = :draft_key AND sequence < :sequence", draft_key: key, user_id: user_id, sequence: c.sequence)
     c.sequence
   end
 

spec/models/draft_spec.rb

@@ -42,6 +42,7 @@ describe Draft do
       _t = Fabricate(:topic, user: u)
       s = DraftSequence.current(u, Draft::NEW_TOPIC)
       expect(Draft.get(u, Draft::NEW_TOPIC, s)).to eq nil
+      expect(Draft.count).to eq 0
     end
 
     it 'nukes new pm draft after a pm is created' do