Revert "Merge pull request #14269 from arthurnn/expanded_key_array"

This reverts commit 475c96589c, reversing
changes made to 705915ab5c.

We decided that this is not worth busting everyone's cache as this
seems like a very unlikely problem. The problem only occurs when the
user is 1) not using a namespace, or 2) using the same namesapce for
different *kinds* of cache items. The recommended "fix" is to put
those cache items into their own namspace:

    id = 1
    Rails.cache.fetch(id, namespace: "user"){ User.find(id) }

    ids = [1]
    Rails.cache.fetch(ids, namespace: "users"){ User.find(ids) }

See the discussion on #14269 for details.

activesupport/CHANGELOG.md

@@ -1,8 +1,3 @@
-*   Cache key should add a trailing slash when the key is an array,
-    so `cache.fetch('foo')` and `cache.fetch(['foo'])` wont conflict.
-
-    *arthurnn*
-
 *   Change the signature of `fetch_multi` to return a hash rather than an
     array. This makes it consistent with the output of `read_multi`.
 

activesupport/lib/active_support/cache.rb

@@ -511,7 +511,7 @@ module ActiveSupport
         # called. If the key is a Hash, then keys will be sorted alphabetically.
         def expanded_key(key) # :nodoc:
           return key.cache_key.to_s if key.respond_to?(:cache_key)
-          trailing_slash = false
+
           case key
           when Array
             if key.size > 1
@@ -519,12 +519,11 @@ module ActiveSupport
             else
               key = key.first
             end
-            trailing_slash = true
           when Hash
             key = key.sort_by { |k,_| k.to_s }.collect{|k,v| "#{k}=#{v}"}
           end
-          key = key.to_param
-          trailing_slash ? "#{key}/" : key
+
+          key.to_param
         end
 
         # Prefix a key with the namespace. Namespace and key will be delimited

activesupport/test/caching_test.rb

@@ -257,10 +257,6 @@ module CacheStoreBehavior
     assert_nil @cache.fetch('foo') { 'baz' }
   end
 
-  def test_fetch_with_array_and_without
-    assert_not_equal @cache.fetch('foo') { 'barz' }, @cache.fetch(['foo']) { 'barr' }
-  end
-
   def test_should_read_and_write_hash
     assert @cache.write('foo', {:a => "b"})
     assert_equal({:a => "b"}, @cache.read('foo'))
@@ -353,7 +349,7 @@ module CacheStoreBehavior
 
   def test_array_as_cache_key
     @cache.write([:fu, "foo"], "bar")
-    assert_equal "bar", @cache.read("fu/foo/")
+    assert_equal "bar", @cache.read("fu/foo")
   end
 
   def test_hash_as_cache_key