raises a warning.  Patterns that can only match empty strings are now
rejected.

prevent corrupting exported buffer.

prevent corrupting exported buffer.

Used PyMem_New to check overflow.

Used PyMem_New to check overflow.

Used PyMem_New to check overflow.

and PyObject_AsWriteBuffer().

and PyObject_AsWriteBuffer().

Don't use yield/yield-from in an except block of a generator. Store the
exception and handle it outside the except block.