Only reset the frame backlink of *internally* created exception tracebacks in generators/coroutines, not the ones stored away from the caller state.

Also make some C function signatures generic to avoid a dependency on concrete struct types in "far away" code.

Terminate generator in test to avoid having its exception state hang around, which leads to exception leaks in Py3.3 for the pure Python comparison test.

Check frame back-pointer before we clear it. CPython can simply assert the identity in genobject.c because it always owns a frame itself for the current coroutine. Since Cython does not have frames here and uses the last frame of whatever traceback it currently owns, it's not clear if we can really give any guarantees better than best-effort here.

Move exception state cleanup into generator body code to allow a distinction between normal yields and yields in except blocks. They require different handling according to what CPython does.

Add a script that concatenates the code sections in CPython's ceval.c in the execution sequence given by the byte code of a Python function.

Prevent incorrect coercion from digit-only strings to integers in fallback code if slots are not used (e.g. in PyPy).

Extend test to assure that normal conversion to C integers does not allow strings, but only (optimised) casting does.

Disable refnanny in PyPy since it otherwise risks to access partly initialised objects, e.g. tuples.

https://github.com/python/typeshed/pull/1554#discussion_r134561386

Remove accidental left-over name "gs" from Shadow.py that should not be part of the pure mode types.

Avoid some unnecessary strlen() calls in exception text formatting, while still keeping up the nice property of sharing const C message strings.

Revert "Do not compile Lexicon.py. It's really only used once and is much larger as a binary module than as a byte code file, but not slower to import."
Currently seems to be required when the scanner is compiled.
This reverts commit d66405c6.

Do not compile Lexicon.py. It's really only used once and is much larger as a binary module than as a byte code file, but not slower to import.

Keep direct closure of generators and coroutines intact during cleanup by disabling their tp_clear() as they still need their closure for handling the final GeneratorExit call.

See #1731.