Only work out newly_joined_users for incremental sync
Only work out newly_joined_users for incremental sync

TribeMedia/synapse,TribeMedia/synapse,matrix-org/synapse,matrix-org/synapse,TribeMedia/synapse,TribeMedia/synapse,TribeMedia/synapse,matrix-org/synapse,matrix-org/synapse,matrix-org/synapse,matrix-org/synapse