> Changes f_lasti, tb_lasti etc to count code units instead of bytes.

I asked Demur to not break f_lasti. I don't understand if this change
breaks applications using f_lasti or not.

For example, asyncio/coroutines.py uses:

            if caller.f_code.co_code[caller.f_lasti] != _YIELD_FROM:
                value = value[0]

Does this code still work with your change?

Maybe this code is already broken by wordcode, but it doesn't really
matter since it should only be used on the exact version 3.4.0. The
code works around a bug in Python 3.4.0, fixed in Python 3.4.1 (issue
#21209).

Other known users of f_lasti are development tools like debuggers
(pdb), profilers, code coverage, etc. We should check these tools.