When the user presses the "Discard changes" button when creating a Content Type, it will be stored in the database, but won't be accessible from anywhere in the Admin UI, which may lead to unexpected behavior, like an impossibility to delete empty Content Type Group.
Steps to reproduce
1. Clean installation of eZ Platform 2.5.9
2. Log in as admin to the backofice.
3. Create Content Type Group Test Group.
4. In Test Group click on "plus" button. In "Creating a new Content Type" view click on "Discard changes".
5. Go back to Content Type Groups list and select Test Group. Click on the "trash" button to delete selected Content Type.
Content Type is deleted normally.