This has driven me crazy for *months* now and I finally figured out what's going on (mostly). python-mode.el has `py--run-auto-fill-timer` which calls `py--set-auto-fill-values` at random times. This will set `fill-column` to the value of `py-docstring-fill-column`. I have `py-docstring-fill-column` set to 100, but `fill-column` defaults to 78. The problem I'm seeing is that `fill-column` gets set to 100 even in non-python-mode buffers. F.e. I'm editing a `.rst` file and kept seeing its `fill-column` getting set from 78 to 100 at completely random times! No matter how often I explicitly set `fill-column` back to 78, it kept getting reset to 100. Now I know how it's happening but I don't know why this will set `fill-column` in random non-py buffers, especially when the variable is buffer local. What's going on here?