Message11434

I tested this using the attached program mem_test.java.
Note that in this form it requires a minimally modified Jython-build. For simplicity of testing this I changed PySystemState.sysClosers to be public.
Indeed it turns out that PySystemState.sysClosers.size() is constantly growing, about 40 per 500 iterations. After 20000 iterations I have 1541 sysClosers.
So, even if this might not be much notable in memory load, I'd call it some kind of leak. As next step I will check if the proposed solution cures this...