This isn't really true. The Google oss policies (opensource.google) require that you use a recent version. As a result upatreaming functional changes is encoura

This isn't really true. The Google oss policies (opensource.google) require that you use a recent version. As a result upatreaming functional changes is encouraged and easier than maintaining a local patch set. Sometimes there are local changes but they're usually non functional stuff to make the library integrate with google infra. They do vendor, but that's for security and efficiency reasons mostly, not to avoid giving back.