(2.6 is security fix only)

Stripping truly dead code after return is really tricky in general because
a) it might be in a conditional block, and 
b) unreachable yield and assignment can affect compilation.
Assignments that make names local are detected on a first pass, but I do not know about yield. Anyway, I believe the policy has been to not do it.

The final patch will need a cpython-only test based on g(x), with dead code.

Possibly intersecting issues are proposals to change where optimization is done and, for testing, to add a generator to dis so its output can be directly captured and analyzed instead of having to redirect, capture, and parse stdout.