Incompatible Symbol#to_proc was reverted upstream

activesupport/lib/active_support/core_ext/symbol.rb

-# Remove 1.8.7's incompatible method.
-if :to_proc.respond_to?(:to_proc) && [1] != ([[1, 2]].map(&:first) rescue false)
-  class Symbol
-    remove_method :to_proc
-  end
-end
-
 unless :to_proc.respond_to?(:to_proc)
   class Symbol
     # Turns the symbol into a simple proc, which is especially useful for enumerations. Examples: