Paul,

You are right.  I misunderstood that comment myself.  I've tried the 
attached modification to your patch (unreachable-code-1.diff) and it 
passes all tests while fixing msg62953  problem:

$ cat t.py 
def f():
    return 1
    1+2
from dis import dis
dis(f)

$ ./python.exe t.py
  6           0 LOAD_CONST               0 (None)
              3 RETURN_VALUE