Issue #2143415 by YesCT, mikeryan, marvil07, bdone, chx: Migrate fixes

core/modules/migrate/lib/Drupal/migrate/Entity/Migration.php

.../modules/migrate/lib/Drupal/migrate/MigrateExecutable.php

...grate/lib/Drupal/migrate/Plugin/MigrateIdMapInterface.php

...rate/lib/Drupal/migrate/Plugin/MigrateSourceInterface.php

.../migrate/lib/Drupal/migrate/Plugin/migrate/id_map/Sql.php

...rate/lib/Drupal/migrate/Plugin/migrate/source/SqlBase.php

core/modules/migrate/lib/Drupal/migrate/Row.php

...ules/migrate/lib/Drupal/migrate/Tests/MigrateTestBase.php

...migrate/tests/Drupal/migrate/Tests/FakeDatabaseSchema.php

...modules/migrate/tests/Drupal/migrate/Tests/FakeSelect.php

...rate/tests/Drupal/migrate/Tests/MigrateExecutableTest.php

...es/migrate/tests/Drupal/migrate/Tests/MigrateTestCase.php