bug#51146: 29.0.50; file-notify-add-watch not reporting changes of files

[Carlos Pita]

According to https://news.ycombinator.com/item?id=9063910 the difference
I noticed is in fact a difference between kqueue and inotify.

This is the only disclaimer the elisp manual does wrt kqueue:

     Likewise, the kqueue library does not report reliably file
     attribute changes when watching a directory.

So nothing about changes in file contents. Given that the documentation
also states:

     Since all these libraries emit different events on notified file
     changes, there is the Emacs library filenotify which provides a
     unified interface. Lisp programs that want to receive file
     notifications should always use this library in preference to the
     native ones.

I think that either this is a bug or the documentation is very
misleading in that the library provides a unified interface. If it is a
bug, it doesn't seem to be an easy cure, at least if we are to believe
what was said in the referenced ycombinator thread.

Best regards,
Carlos