Is contained in /reddit/r2/r2/lib/pages/pages.py
This file is pretty huge, and it seems to contain a ton of stuff. I think it's sort of a non-page-specific catch-all file used by the HTML generation .py files.
I made edits and entry deletions to the navbar sections of this file, in only the parts relating to the navigation bar. The original file was saved to pages_original.py