Province qualifies as nation too.

src/engine/net/client/handlers/SwearInGuildHandler.java

@@ -101,7 +101,8 @@ public class SwearInGuildHandler extends AbstractClientMsgHandler {
             GuildManager.updateAllGuildTags(protectorate);
 
             if (nation.guildState == GuildState.Sovereign)
-                if (protectorate.guildState.equals(GuildState.Protectorate))
+                if (protectorate.guildState.equals(GuildState.Protectorate) ||
+                        protectorate.guildState.equals(GuildState.Province))
                     nation.guildState = GuildState.Nation;
 
             SendGuildEntryMsg msg = new SendGuildEntryMsg(player);

src/engine/objects/Guild.java

@@ -741,8 +741,6 @@ public class Guild extends AbstractWorldObject {
 
         this.guildState = GuildManager.calcuateGuildState(this);
 
-        Logger.info(this.name + ":" + this.guildState + ":" + this.nation.name);
-
         if (this.getOwnedCity() == null)
             return;