2.4-stable: revert r13114 (#16685)

git-svn-id: http://svn.redmine.org/redmine/branches/2.4-stable@13121 e93f8b46-1217-0410-a6f0-8f06a7374b81

Gemfile

@@ -6,7 +6,6 @@ gem "jquery-rails", "~> 2.0.2"
 gem "coderay", "~> 1.1.0"
 gem "fastercsv", "~> 1.5.0", :platforms => [:mri_18, :mingw_18, :jruby]
 gem "builder", "3.0.0"
-gem "request_store"
 
 # Optional gem for LDAP authentication
 group :ldap do

app/models/user.rb

@@ -607,11 +607,11 @@ class User < Principal
   end
 
   def self.current=(user)
-    RequestStore.store[:current_user] = user
+    Thread.current[:current_user] = user
   end
 
   def self.current
-    RequestStore.store[:current_user] ||= User.anonymous
+    Thread.current[:current_user] ||= User.anonymous
   end
 
   # Returns the anonymous user.  If the anonymous user does not exist, it is created.  There can be only