Merge pull request rails#5112 from nupurjain/activesupport_cache_refactor

suggested changes.

Author: spastorino

activesupport/lib/active_support/cache.rb

@@ -382,11 +382,7 @@ def exist?(name, options = nil)
         options = merged_options(options)
         instrument(:exist?, name) do |payload|
           entry = read_entry(namespaced_key(name, options), options)
-          if entry && !entry.expired?
-            true
-          else
-            false
-          end
+          entry && !entry.expired?
         end
       end