State of RocksDB

What is the state of RocksDB for Rust?

It seems to me there are three versions:

  2. Parity fork of 1,
  3. PingCAP fork of 1,

What are the changes and why are they forked?

Now the main repository is under organization,, but Parity/PingCAP forks still exist and I am still mystified. Does anyone know?