Note that the callback is in 4.0-trunk now

README

@@ -17,6 +17,8 @@ INSTALLATION
         line.
 
     patch RT
+        If you are running RT 4.0.7 or earlier:
+
             patch -d /opt/rt4 -p1 < etc/callback_before_localization.diff
 
     Clear your mason cache

lib/RT/Extension/LocalDateHeader.pm

@@ -30,6 +30,8 @@ or add C<RT::Extension::LocalDateHeader> to your existing C<@Plugins> line.
 
 =item patch RT
 
+If you are running RT 4.0.7 or earlier:
+
     patch -d /opt/rt4 -p1 < etc/callback_before_localization.diff
 
 =item Clear your mason cache