Require 'pty' not working on Solaris

Greetings,
just trying our jruby-1.6.1 on a Solaris (10) system. I was looking at
using
the pty library but get the following error

$jruby -vrpty -e ‘p 0’
jruby 1.6.1 (ruby-1.8.7-p330) (2011-04-12 85838f6) (Java HotSpot™
Client VM
1.6.0_23) [SunOS-x86-java]
FFI::NotFoundError: Function ‘forkpty’ not found in [libc.so]
attach_function at
/usr/bin/…/jruby/lib/ruby/site_ruby/shared/ffi/library.rb:100
each at org/jruby/RubyArray.java:1602
attach_function at
/usr/bin/…/jruby/lib/ruby/site_ruby/shared/ffi/library.rb:96
LibUtil at
/usr/bin/…/jruby/lib/ruby/site_ruby/shared/pty.rb:12
PTY at
/usr/bin/…/jruby/lib/ruby/site_ruby/shared/pty.rb:5
(root) at
/usr/bin/…/jruby/lib/ruby/site_ruby/shared/pty.rb:3

Some ‘googling’ seems to indicate that forkpty is not something that
exists on
Solaris but:

There is an open issue against the pty library
(http://jira.codehaus.org/browse/JRUBY-5584) but the note in that JIRA
says:

‘The error only affects the jruby-complete-X.jar version; in the binary
Jruby
.tar.gz or .zip versions the ‘pty’ library works normally’

So I must be missing something in my setup. Any ideas on what I should
try or
look for? I am not a developer and don’t exactly know where to start
looking…

Regards,
Dany