rewrite user lang forum cache key

modules/forum/src/main/Recent.scala

@@ -27,9 +27,11 @@ final class Recent(
 
   def invalidate(): Unit = cache.invalidateAll
 
+  private val defaultLang = "en"
+
   private def userCacheKey(user: Option[User], getTeams: GetTeamIds): Fu[String] =
     (user.map(_.id) ?? getTeams).map { teamIds =>
-      user.fold("en")(_.langs.mkString(",")) :: {
+      user.fold(defaultLang)(u => (defaultLang :: u.lang.filter(defaultLang !=).toList).mkString(",")) :: {
         categIds ::: teamIds.view.map(teamSlug).toList
       } mkString ";"
     }

modules/user/src/main/User.scala

@@ -41,8 +41,6 @@ case class User(
 
   def realNameOrUsername = profileOrDefault.nonEmptyRealName | username
 
-  def langs = ("en" :: lang.toList).distinct.sorted
-
   def compare(other: User) = id compareTo other.id
 
   def disabled = !enabled