Fix #4940: DanbooruBot retiring banned_artist implications.

app/logical/tag_relationship_retirement_service.rb

@@ -40,13 +40,20 @@ module TagRelationshipRetirementService
   end
 
   def inactive_relationships
-    (inactive_aliases + TagAlias.active.empty + TagImplication.active.empty).uniq
+    (inactive_aliases + inactive_implications).uniq
+  end
+
+  def inactive_implications
+    TagImplication.active.empty.where.not(consequent_name: "banned_artist")
   end
 
   def inactive_aliases
     aliases = TagAlias.general.or(TagAlias.artist).active.where("tag_aliases.created_at < ?", THRESHOLD.ago)
-    aliases.select do |tag_alias|
+    aliases = aliases.select do |tag_alias|
       !tag_alias.consequent_tag.posts.exists?(["created_at > ?", THRESHOLD.ago])
     end
+
+    aliases += TagAlias.active.empty
+    aliases
   end
 end

app/models/tag.rb

@@ -356,6 +356,14 @@ class Tag < ApplicationRecord
     cosplay_tags.grep(/\A(.+)_\(cosplay\)\Z/) { "#{TagAlias.to_aliased([$1]).first}_(cosplay)" } + other_tags
   end
 
+  def implied_tags
+    TagImplication.tags_implied_by([name])
+  end
+
+  def implies?(tag_name)
+    implied_tags.exists?(name: tag_name)
+  end
+
   def posts
     Post.system_tag_match(name)
   end