On AIX, io/console.rb is broken for all versions of JRuby 9k including 9.0.4.
The error displayed is

TypeError: no implicit conversion of nil into String reopen at org/jruby/RubyIO.java:582 <top> at uri:classloader:/META-INF/jruby.home/lib/ruby/stdlib/io/console.rb:202

The reason is that the call $stderr.dup in line 195 fails:
NotImplementedError: dup unsupported or native support failed to load

This error is caught, but the subsequent try to reopen old_stderr fails in line 202.