Clear active connections before trying to drop the database. Allows db:drop to work with posgresql. Closes #10559 [jqr]

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@8876 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

railties/lib/tasks/databases.rake

@@ -344,6 +344,7 @@ def drop_database(config)
   when /^sqlite/
     FileUtils.rm(File.join(RAILS_ROOT, config['database']))
   when 'postgresql'
+    ActiveRecord::Base.clear_active_connections!    
     `dropdb "#{config['database']}"`
   end
 end