bug#56682: locked narrowing

[Gregory Heytings]

> There is another side-effect: after evaluating manually 'M-: 
> (pos-visible-in-window-p) RET' at the position 1000000, point moves to 
> the position 749873 afterwards.  It seems this is related to locked 
> narrowing, because point doesn't jump after customizing 
> long-line-locked-narrowing-region-size to 0.

I cannot reproduce that.  With the following recipe:

emacs -Q
C-x C-f dictionary.json RET
M-g c 1000000 RET
M-: (pos-visible-in-window-p) RET

point does not move.  Is there something missing in that recipe?