carrierwaveuploader/carrierwave — pull request #1447 by huacnlee (2014-08-27 15:35:18+00:00)
Title: Fix bug with remove_previously_stored_#{column} callback, when updating in a transaction, and that process is rollback

Fix bug with remove_previously_stored_#{column} callback, when updating in a transaction, and that process is rollback

The old file will be delete, but the new file name can not store success into database.

## For example:

```ruby
User.transaction do
@user.avatar = new_file
@user.save
# new file stored
# old file deleted with callback: remove_previously_stored_avatar
# ... do bla bla
raise ActiveRecord::Rollback
# new file name can not update to datebase
end
```