Clean field_collection data, when migrating existing fields

fix-fields.drush

#!/usr/bin/env drush

$result = db_query("SELECT id, data from field_config where type = 'field_collection'");
foreach ($result as $field) {
  $data = unserialize($field->data);
  $data['indexes'] = array('revision_id' => array('revision_id'));
  $data = serialize($data);
  db_query("update field_config set data = :data where id = :id", array(':data' => $data, ':id'=> $field->id));
}