Replication issue with actors not being attached to sockets

If the client received AttachSocketName before AttachParent, USceneComponent::AttachToComponent will be called while AttachParent may be null, resulting in the received socket name being lost. When AttachParent is then received, USceneComponent::AttachToComponent will be called without the correct socket name. 

1. Create replicated actor on server.
2. Spawn another replicated actor to be attached to the first on a certain socket.

Expected:

Replicated actor will be attached to the first on the specified socket.

Actual:

Slight chance that the actor will not be attached on any socket.