[$] The Grumpy Editor's Python 3 experience

LWN has been running articles for years to the effect that the end ofPython 2 is nigh and that code should be ported to Python 3immediately. So, naturally, one might expect that our own site code, written in Python, had beenforward-ported long ago. Strangely enough, that didn't actually happen.It has mostly happened now, though. In the process of doing thiswork, your editor has noticed a few things that don't necessarily appear inthe numerous porting guides circulating on the net.