sqlite3_mem tests are broken since 79887593

since 79887593, create_all task recreates the connection to AR::Base
which doesn't connect to the in_memory database that is set up for tests

activerecord/test/cases/tasks/database_tasks_test.rb

@@ -100,6 +100,8 @@ def setup
       @configurations = { "development" => { "database" => "my-db" } }
 
       ActiveRecord::Base.stubs(:configurations).returns(@configurations)
+      # To refrain from connecting to a newly created empty DB in sqlite3_mem tests
+      ActiveRecord::Base.connection_handler.stubs(:establish_connection)
     end
 
     def test_ignores_configurations_without_databases