Unable to set __persistent__

Hello all.
When I attempt to run the demos here:

I get this:

jruby test.rb
JavaProxy$INVOKER$i$1$0$persistent.gen:-1:in call': java.lang.ClassCastException: org.jruby.RubyClass cannot be cast to org.jruby.java.proxies.JavaProxy from CachingCallSite.java:312:in cacheAndCall’
from CachingCallSite.java:169:in call' from test.rb:9:in file’
from test.rb:-1:in load' from Ruby.java:778:in runScript’
from Ruby.java:771:in runScript' from Ruby.java:648:in runNormally’
from Ruby.java:497:in runFromMain' from Main.java:375:in doRunFromMain’
from Main.java:264:in internalRun' from Main.java:230:in run’
from Main.java:214:in run' from Main.java:194:in main’

(hard exit)

is this expected?

jruby 1.7.0.preview1 (ruby-1.9.3-p203) (2012-05-17 c550df6) (Java
HotSpot™ Client VM 1.6.0_32) [Windows 7-x86-java]

Reported and fixed on master.

Appears fixed with jruby 1.7.0.preview2.dev (ruby-1.9.3-p203)
(2012-06-14 fb4c77f)
Thanks!
-roger-