Use object pools for forks of the fork

Problem

flowchart LR
A["Project A (root)"] -- fork --> B["Project B (fork)"] -- fork --> C["Project C (fork of the fork)"]
A---|connected to Project A|P["Object pool"]
B-.linked.->P

When the Project A is forked, then we create an object pool connected to the Project A. All direct forks of this project are linked to the same object pool.

However, forks or the fork (like Project C) are not connected to any pools.

Proposal

Consider to remove !forked? condition before fork process.

When Project C is forked from Project B, then Project C should be linked to the Project A object pool.

Additional context: !127143 (comment 1506603389)

Potential problems

1. When Project A becomes private we unlink its forks from the object pool. However, we might do it only for direct forks.
2. What if Project B becomes private, should we unlink Project C as well?