Trouble installing gem with cext on JRuby 1.6.0.RC2 : bond

So I was installing gems for JRuby 1.6.0.RC2. In my JRuby 1.6.0.RC1
installation, the ruby.h include directory is found under
C:/jruby-1.6.0.RC1/lib/native/include.

Under RC2, it’s C:/jruby-1.6.0.RC2/cext/src/include.

So when I try to install bond, I get this error:

PS C:\jruby-1.6.0.RC2\bin> .\jruby.bat -S gem install bond
Fetching: bond-0.4.0.gem (34304B)
Building native extensions. This could take a while…
ERROR: Error installing bond:
ERROR: Failed to build gem native extension.

    C:/jruby-1.6.0.RC2/bin/jruby.exe extconf.rb

WARNING: JRuby does not support native extensions or the `mkmf’ library
very
well.
Check http://kenai.com/projects/jruby/pages/Home for alternatives.
mkmf.rb can’t find header files for ruby at
C:/jruby-1.6.0.RC2/lib/native/include/ruby/ruby.h

Gem files will remain installed in
C:/jruby-1.6.0.RC2/lib/ruby/gems/1.8/gems/bond-0.4.0 for inspection.
Results logged to
C:/jruby-1.6.0.RC2/lib/ruby/gems/1.8/gems/bond-0.4.0/ext/readline_line_buffer/gem_make.out
PS C:\jruby-1.6.0.RC2\bin> type
C:/jruby-1.6.0.RC2/lib/ruby/gems/1.8/gems/bond-0.4.0/ext/readline_line_buffer/gem_make.out
C:/jruby-1.6.0.RC2/bin/jruby.exe extconf.rb
WARNING: JRuby does not support native extensions or the `mkmf’ library
very
well.
Check http://kenai.com/projects/jruby/pages/Home for alternatives.
mkmf.rb can’t find header files for ruby at *
C:/jruby-1.6.0.RC2/lib/native/include/ruby/ruby.h*
PS C:\jruby-1.6.0.RC2\bin>

-Nick K.

I thought this hadn’t been posted to the forum or got lost, so I
apologize if this duplicates the symptoms reported from a more recent
post:

http://www.ruby-forum.com/topic/1067212