Don't try to support old cluster versions in the directory_read_manager, when we don't do it anywhere else in the cluster code.
Removed version parameter to on_message()
fixing build
Merge branch 'next' of github.com:rethinkdb/rethinkdb into next
merge of #2583 zombie server processes

Found that not all rethinkdb server processes were being shut down because we were relying on __exit__ being called when it goes out of scope. But those handlers are not generally called when the process exits.
Merge remote-tracking branch 'origin/next' into larkost/2531-python-3-v2