But if the product is already working, chances are that you get away long enough (to do a graceful migration) by just doing small bug fixes, changes to support OS updates, etc.
This is what we are now doing for a project with Berkeley DB XML, which hadn't seen updates for five years. When there finally was an update, it was buggy and moved to the Affero GPL 3, which conflicts with other open source licenses used in the project. So, we continue to use the five year old iteration with a small set of patches.
(Lesson learned: once a product is owned by Oracle, prepare your evacuation plans.)
This is what we are now doing for a project with Berkeley DB XML, which hadn't seen updates for five years. When there finally was an update, it was buggy and moved to the Affero GPL 3, which conflicts with other open source licenses used in the project. So, we continue to use the five year old iteration with a small set of patches.
(Lesson learned: once a product is owned by Oracle, prepare your evacuation plans.)