Fix stateless-iso-2022-jp

Issue #4348 has been updated by Yuki S…

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applied at r31197.
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Backport #4348: fix stateless-iso-2022-jp
http://redmine.ruby-lang.org/issues/4348

Author: Nobuyoshi N.
Status: Assigned
Priority: Normal
Assignee: Yuki S.
Category: M17N
Target version:

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r30727とr30727のバックポートをお願いします。
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