Large functions with size of a bytecode bigger than
65535 bytes may be incorrectly optimized by
"optimize_code" in "Python/compile.c". Optimalization
happens automaticaly during loading from *.pyc and
cannot be disabled. Codes loaded directly from source
(*.py) are not optimalized and not affected by this bug.

One of task of "optimize_code" is to eliminate
"chained" jumps  (when one of jumps points directly to
unconditional jump). Problems occurs when a first jump
opcode points to JUMP_FORWARD, which target is after
64K boundary. This target adress is copied as absolute
address of the first jump modulo 2**16.

This bug can lead to different symptoms during
execution of a code. You can get an "unknown opcode"
error, but  sometimes results can be unpredicable.

This problem appears in Python 2.3 (tested) and
possibly in 2.4 (alfa). 

Attached scripts generates large functions a writes
disassebles before and after optimalization. You will
find, that some adresses after optimalization are bad.