these two messages maybe give you hints / ideas:
>> Are there any problems running Jython (2.1 or the alpha) on JVM 1.5?
> I don't think 2.1 runs on 1.5 out of the box. It needs to be recompiled
> (and maybe a minor patch or two?) to run on 1.5. Someone posted a link
> to a recompiled jar a while ago but I can't find it right now...
IIRC, there were several issues with compiling jython 2.1 in java 1.5,
including a keyword naming clash due to the introduction of the "enum"
keyword in java 1.5.
If someone has a patched jython 2.1 which is ready to run on java 1.5, I
think it would be an excellent idea to make a java1.5-specific download
available. I think the availability of this would go a long way to
answering the "jython is dead" critics.
I depend heavily on jython 2.1 in my production setups, and have been
avoiding upgrading to java 1.5 precisely because of such issues.
While I eagerly await the availability of jython 2.2+ (generators and
coroutines on java: cool B-) it would be nice for the 100% stable and
reliable jython 2.1 to be usable right now on jdk 1.5.