bug#7221: timestamp in cvs-quickdir on Win32 system

[Eli Zaretskii <eliz@gnu.org>]

> Date: Fri, 27 Aug 2021 01:06:56 +0200
> From: Rolf Unger <rz.unger@web.de>
> Cc: Eli Zaretskii <eliz@gnu.org>, Stefan Kangas <stefan@marxist.se>,
> 	7221@debbugs.gnu.org
> 
> I gave it a go with your suggested patch, and it still marks some files as
> modified that are not modified.
> 
> Maybe I should give some details to my constellation:
> My working directory is on a win32 machine, but the repository is on a
> Linux box and I use the pserver protocol to access the repository.
> My Project resides all in one directory, it consists of two .c files, a
> header file and some Windows resource script files .rc. Furthermore I have
> a Makefile for MinGW gnu make and one .mak file for nmake.
> 
> The Makefile, the .mak and the .rc resource files are marked as modified
> if I open the project directory with `csv-quickdir`. The .c files and the
> header file are not shown (the rule for files that are up-to-date)
> If I use cvs-status on this same directory all files are shown as
> up-to-date (which is the same what I get if I run `cvs status` in a shell.
> 
> The interesting part is: If I open a file (the Makefile for example) with
> `o` in the other window the *cvs* buffer will immediately show the file
> that have just opened as `modidied`. But I haven't done any changes in
> that opened file, only the active cursor is in that buffer.
> If I hit `g` to refresh the *cvs* buffer with (cvs -f -n update -d -P)
> the opened file that is said to be modified will transition to Up-To-Date
> again.
> I thought it could be related with the character encoding because the .rc
> files are UTF-8 encded and theser .rc files are shown as modified.
> But if it is a encoding issue it should not happen for the Makefile,
> because this file as ASCII clean file.
> 
> If I execute `vc-dir` on my project only some unregistered files are
> shown, because vc doesn't show files that are not modified.
> So `vc` does show the status of the files correctly.
> 
> All this strange behaviour let's me guess, that the problem is not within
> the elisp code and maybe wrong assumptions on the date format of cvs'
> timestamp of the revision.

Your setup is sufficiently complicated, even exotic, to be hard to
reproduce and to be able to produce problems due to quite a few
factors.  Can you step through the Lisp code relevant to the issue,
and see what causes Emacs to decide the files are modified?  If it's
the problem with time stamp mismatch, can you show an example of
timestamps that should match, but don't?

Thanks.