checked all .rb files in the project tree for missing magic comments, one was missing

Came with this one-liner for this:

    find . -name '*.rb' | \
    xargs chardet | \
    grep -v ascii | \
    cut -d: -f1 -s | \
    xargs -n1 ruby -0777 -ne 'puts $FILENAME if $_ !~ /#.*coding:\s*utf/i'

Welcome $_.

actionpack/lib/action_view/helpers/number_helper.rb

@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'active_support/core_ext/big_decimal/conversions'
 require 'active_support/core_ext/float/rounding'
 require 'active_support/core_ext/object/blank'

activesupport/test/json/decoding_test.rb

@@ -1,4 +1,4 @@
-# encoding: UTF-8
+# encoding: utf-8
 require 'abstract_unit'
 require 'active_support/json'
 require 'active_support/time'