bug#57669: 29.0.50; C-n, C-p off under long lines

[Gregory Heytings]

> This is an uncontrived, "in the wild" log file that I was C-n and 
> C-p'ing when I discovered this "non-problem."

I'm not sure what that file is supposed to demonstrate?  Yes, sometimes 
point moves to another column.  Why is that a problem while navigating 
through that particular file?  Is Emacs unusable?

> I speculate at least half your users would consider this a regression, 
> although perhaps not one serious enough to revert your changes.  Some of 
> them would consider this a bug.

If you have ideas to improve the situation in one way or another, feel 
free to share them.