2011/11/25  <kosaki / ruby-lang.org>:
> kosaki  2011-11-25 08:02:44 +0900 (Fri, 25 Nov 2011)
>
>  New Revision: 33834
>
>  http://svn.ruby-lang.org/cgi-bin/viewvc.cgi?view=rev&revision=33834
>
>  Log:
>    * lib/mkmf.rb: get rid of warnings of mkmf.rb if -Wmissing-declarations
>      and/or -Wold-style-definition warnings if specified.
>      Patch by Nikolai Weibull. Thank you! [Bug #5459] [ruby-core:40200]
>
>  Modified files:
>    trunk/ChangeLog
>    trunk/lib/mkmf.rb

たぶんこれだと思うのですが、dbm が build されなくなっています。

http://www.rubyist.net/~akr/chkbuild/debian/ruby-trunk/log/20111124T231300Z.diff.html.gz

...
configuring dbm
Failed to configure dbm. It will not be installed.
configuring digest
...
-- 
[田中 哲][たなか あきら][Tanaka Akira]