Fix spec by removing global state.

lib/gitlab/reply_by_email.rb

@@ -36,7 +36,6 @@ module Gitlab
       end
 
       def address_regex
-        @address_regex ||= begin
         wildcard_address = config.address
         return nil unless wildcard_address
 
@@ -47,4 +46,3 @@ module Gitlab
     end
   end
 end
-end