Remove rack-cache-purge.

actionpack/actionpack.gemspec

@@ -22,7 +22,6 @@ Gem::Specification.new do |s|
   s.add_dependency('activesupport',    version)
   s.add_dependency('activemodel',      version)
   s.add_dependency('rack-cache',       '~> 0.5.3')
-  s.add_dependency('rack-cache-purge', '~> 0.0.1')
   s.add_dependency('builder',          '~> 2.1.2')
   s.add_dependency('i18n',             '~> 0.4.1')
   s.add_dependency('rack',             '~> 1.2.1')

actionpack/lib/action_dispatch/http/rack_cache.rb

@@ -21,11 +21,6 @@ module ActionDispatch
       @store.write(key, value)
     end
 
-    def purge(key)
-      @store.delete(key)
-      nil
-    end
-
     ::Rack::Cache::MetaStore::RAILS = self
   end
 
@@ -58,10 +53,6 @@ module ActionDispatch
       [key, size]
     end
 
-    def purge(key)
-      @store.delete(key)
-    end
-
     ::Rack::Cache::EntityStore::RAILS = self
   end
 end