NotImplementedError bypasses rescue clause in Ruby 1.8.7 (REE)

NotImplementedError_bypasses_rescue_clause.rb

# Tested under:
# $ ruby -v
# ruby 1.8.7 (2010-04-19 patchlevel 253) [i686-darwin10.4.0], MBARI 0x6770, Ruby Enterprise Edition 2010.02

class C
  def f
    raise NotImplementedError
  end
end

begin
  result = C.new.f
rescue => e
  if result.kind_of?( Exception ) then
    puts 'result is an Exception'
  else
    puts 'result was not an Exception'
  end
end

# Output is:
# NotImplementedError_bypasses_rescue_clause.rb: ... :in `f': NotImplementedError (NotImplementedError)
#  from NotImplementedError_bypasses_rescue_clause.rb: ...