If we undef <=>, it solves a problem involving comparison. Please figure out the root cause.

Author: wycats

activesupport/lib/active_support/multibyte/chars.rb

@@ -51,6 +51,8 @@ def initialize(string) #:nodoc:
         end
       end
 
+      undef <=>
+
       # Forward all undefined methods to the wrapped string.
       def method_missing(method, *args, &block)
         if method.to_s =~ /!$/