Apply the same punishment logic to the v4 version of antiknocker as v3.

This has been tested and just seems to cause the bot to spam nick
changes until it floods off which is less useful than the alternative.

4/m_antiknocker.cpp

@@ -28,12 +28,6 @@
 #include "extension.h"
 #include "modules/shun.h"
 
-enum
-{
-	// From RFC 1459.
-	ERR_NICKNAMEINUSE = 433
-};
-
 class ModuleAntiKnocker final
 	: public Module
 {
@@ -43,6 +37,26 @@ class ModuleAntiKnocker final
 	unsigned long shunduration;
 	std::string shunreason;
 
+	void PunishUser(LocalUser* user)
+	{
+		auto* sh = new Shun(ServerInstance->Time(), shunduration, MODNAME "@" + ServerInstance->Config->ServerName, shunreason, user->GetAddress());
+		if (ServerInstance->XLines->AddLine(sh, nullptr))
+		{
+			ServerInstance->XLines->ApplyLines();
+			return;
+		}
+
+		// No shunning? Annoying. Just quit em.
+		delete sh;
+
+		std::string message;
+		if (!user->IsFullyConnected())
+			message = "Connection timeout";
+		else
+			message = INSP_FORMAT("Ping timeout: {} seconds", user->GetClass()->pingtime);
+		ServerInstance->Users.QuitUser(user, message);
+	}
+
 	ModuleAntiKnocker()
 		: Module(VF_NONE, "Attempts to block a common IRC spambot.")
 		, seenmsg(this, "seenmsg", ExtensionType::USER)
@@ -89,18 +103,7 @@ class ModuleAntiKnocker final
 				ServerInstance->SNO.WriteToSnoMask('a', "User {} ({}) was caught in an knocker trap!",
 						user->nick, user->GetRealUserHost());
 
-				auto* sh = new Shun(ServerInstance->Time(), shunduration, MODNAME "@" + ServerInstance->Config->ServerName, shunreason, user->GetAddress());
-				if (ServerInstance->XLines->AddLine(sh, nullptr))
-				{
-					ServerInstance->XLines->ApplyLines();
-					return MOD_RES_DENY;
-				}
-
-				// No shunning? Annoying. Just quit em.
-				delete sh;
-
-				const std::string message = INSP_FORMAT("Ping timeout: {} seconds", user->GetClass()->pingtime);
-				ServerInstance->Users.QuitUser(user, message);
+				PunishUser(user);
 				return MOD_RES_DENY;
 			}
 		}
@@ -116,7 +119,8 @@ class ModuleAntiKnocker final
 
 		ServerInstance->SNO.WriteToSnoMask('a', "User {} ({}) was prevented from using a knocker nick: {}",
 			user->nick, user->GetRealUserHost(), newnick);
-		user->WriteNumeric(ERR_NICKNAMEINUSE, newnick, "Nickname is already in use.");
+
+		PunishUser(user);
 		return MOD_RES_DENY;
 	}
 };