Just on the off chance that it’s related, could it have something to do with the bug in findlabels? http://bugs.python.org/issue26448 (I have high confidence that my patch fixes the problem, just haven’t gotten around to completing the tests.) From: Demur Rumed [mailto:gunkmute@gmail.com] Sent: Saturday, April 16, 2016 17:05 To: python-dev@python.org Subject: Re: [Python-Dev] Wordcode: new regular bytecode using 16-bit units The outstanding bug with this patch right now is a regression in line numbers causing the test for http://bugs.python.org/issue9936 to fail. I've tried to debug it without success