Skin changes aren't visible to others if until they restart their client.

How to reproduce:
1. Be on a server with another player.
2. Have them log out, close their client, and change their skin. Then log back on to the server.
3. See that their skin is still not changed.
4. Leave and rejoin server.
5. See that their skin is still not changed.
4. Restart client.
5. See that their skin has changed.