須藤です。

私がお願いしていたこのバックポートなんですが、
  https://bugs.ruby-lang.org/issues/7764

ChangeLogの変更だけがバックポートされていて、実際の変更
  https://bugs.ruby-lang.org/projects/ruby-trunk/repository/revisions/33210
はバックポートされていないようにみえます。
(lib/rexml/parsers/baseparser.rbとかが変更されている。)

確認してもらえないでしょうか?

In <20130206051927.E67E568693 / sakura.atdot.net>
  "[ruby-changes:27041] usa:r39093 (ruby_1_9_3): merge revision(s) 33210,33212: [Backport #5278]" on Wed,  6 Feb 2013 14:19:27 +0900 (JST),
  usa <ko1 / atdot.net> wrote:

> usa	2013-02-06 14:19:18 +0900 (Wed, 06 Feb 2013)
> 
>   New Revision: 39093
> 
>   http://svn.ruby-lang.org/cgi-bin/viewvc.cgi?view=rev&revision=39093
> 
>   Log:
>     merge revision(s) 33210,33212: [Backport #5278]
>     
>     * lib/rexml/parsers/baseparser.rb, test/rexml/test_comment.rb:
>       allow a single hyphen in comment. [Bug 5278]
>       Reported by Thomas Fritzsche. Thanks!!!
>       allow a single hyphen in comment. [Bug #5278] [ruby-core:39289]
> 
>   Modified directories:
>     branches/ruby_1_9_3/
>   Modified files:
>     branches/ruby_1_9_3/ChangeLog
>     branches/ruby_1_9_3/version.h
> 
> Index: ruby_1_9_3/ChangeLog
> ===================================================================
> --- ruby_1_9_3/ChangeLog	(revision 39092)
> +++ ruby_1_9_3/ChangeLog	(revision 39093)
> @@ -1,3 +1,9 @@ https://github.com/ruby/ruby/blob/trunk/ruby_1_9_3/ChangeLog#L1
> +Wed Feb  6 14:19:07 2013  Kouhei Sutou  <kou / cozmixng.org>
> +
> +	* lib/rexml/parsers/baseparser.rb, test/rexml/test_comment.rb:
> +	  allow a single hyphen in comment. [Bug #5278] [ruby-core:39289]
> +	  Reported by Thomas Fritzsche. Thanks!!!
> +
>  Wed Feb  6 14:14:38 2013  Nobuyoshi Nakada  <nobu / ruby-lang.org>
>  
>  	* file.c (realpath_rec): prevent link from GC while link_names refers
> Index: ruby_1_9_3/version.h
> ===================================================================
> --- ruby_1_9_3/version.h	(revision 39092)
> +++ ruby_1_9_3/version.h	(revision 39093)
> @@ -1,5 +1,5 @@ https://github.com/ruby/ruby/blob/trunk/ruby_1_9_3/version.h#L1
>  #define RUBY_VERSION "1.9.3"
> -#define RUBY_PATCHLEVEL 378
> +#define RUBY_PATCHLEVEL 379
>  
>  #define RUBY_RELEASE_DATE "2013-02-06"
>  #define RUBY_RELEASE_YEAR 2013
> 
> Property changes on: ruby_1_9_3
> ___________________________________________________________________
> Modified: svn:mergeinfo
>    Merged /trunk:r33210,33212
> 
> 
> --
> ML: ruby-changes / quickml.atdot.net
> Info: http://www.atdot.net/~ko1/quickml/