bug#13149: 24.3.50; Emacs thinks file was changed outside Emacs, but it was not

[Dmitry Gutov]

On 14.01.2013 21:02, Eli Zaretskii wrote:
> > Date: Mon, 14 Jan 2013 18:57:43 +0400
> > From: Dmitry Gutov <raaahh@gmail.com>
> > Cc: 13149@debbugs.gnu.org
> >
> > Bisect points to revision 110875
> > (eggert@cs.ucla.edu-20121113013514-5dej3lndyeb2dwq3):
> > Fix a race with verify-visited-file-modtime.
> >
> > Since at least 1991 Emacs has ignored an mtime difference of no
> > more than one second, but my guess is that this was to work around
> > file system bugs that were fixed long ago.  Since the race is
> > causing problems now, let's remove that code.
> > * fileio.c (Fverify_visited_file_modtime): Do not accept a file
> > whose time stamp is off by no more than a second.  Insist that the
> > file time stamps match exactly.
>
> Therefore, I doubt that the same problem was the root cause of the
> problem on Drew's laptop.

It hard for me to say, but the symptoms are similar, and the timing 
matches. I think this commit is the likely culprit, although the fix may 
have to be slightly different in Drew's case. Or would be, if we could 
reproduce it.

> > Paul, any suggestions?
>
> I'm not Paul, but can't you synchronize the clocks of the two
> machines?

To the nanosecond? I'm not sure if I can.

But if what you're implying is right, I think rewinding the clock on the 
host machine would also help. It doesn't.