Download parameters if init_parameter failed with already initialized.
Created by: helinwang
(lower priority)
Related code
This will happen when pserver is already initialized, but another trainer thinks it need to initialize the pservers. For example, when not using etcd, the "trainer 0" gets restarted again, it will think it needs to initialize the pserver due to its trainer id is "0".
The correct thing to do is to download parameters if init_parameter failed with "already initialized".