Fix SF #561858 Assertion with very long lists if co_stacksize was > 32767 (the maximum value which can be stored in 16 bits (signed)), the PyCodeObject would be written wrong. So on the second import (reading the .pyc) would cause a crash. Since we can't change the PYC magic, we go on (silently), but don't write the file. This means everything will work, but a .pyc will not be written and the file will need to be parsed on each import. I will backport.