Case statement variation 1.9.2 vs 1.8.7

I have this case statement:

  case n.hll_normalize
    when "common name"
      @my_correspondent.correspondent_common_name = s
    when "legal name"
      . . .
    else
      raise ArgumentError, "#{n} attribute is not provided for."
  end

I pass it this value for n: "common name"

When run with Ruby-1.8.7p302 this works. The exact same code run with
Ruby-1.9.2p0 yields:

common name attribute is not provided for. (ArgumentError)

Is this change in behaviour intentional or a bug? If intentional then
what is the version insensitive way to accomplish the same thing?

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This is the method that we add to String used in the case statement:

  def hll_normalise
    strip.squeeze(" ").mb_chars.downcase
  end

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Sorry, this is evidently a RoR issue. I will move it to there.

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