Better handling custom version

sources/src/main/java/io/akarin/server/mixin/core/MixinVersionCommand.java

@@ -46,6 +46,9 @@ public class MixinVersionCommand {
     private volatile boolean versionObtaining;
     private long lastCheckMillis;
 	
+	private CommandSender currentSender;
+    private boolean customVersion;
+    
     // The name can lead to misunderstand,
     // this method doesn't send the whole version message (e.g. 'This server is running {} version' or 'Previous version'),
     // it is only responsible for checking the version distance!
@@ -80,9 +83,6 @@ public class MixinVersionCommand {
         }
     }
     
-    private CommandSender currentSender;
-    private boolean customVersion;
-    
     @Overwrite
     private void obtainVersion() {
         if (false /* TODO Option: legacy-versioning-compat */) {
@@ -122,6 +122,7 @@ public class MixinVersionCommand {
                         break;
                     case -2:
                         setVersionMessage("Unknown version");
+						customVersion = true;
                         break;
                     default:
                         setVersionMessage("You are " + distance + " version(s) behind");