On 2016-10-30 Sun 09:21 GMT-0700, Eli Zaretskii <eliz@gnu.org> wrote:

>> diff --git a/doc/emacs/maintaining.texi b/doc/emacs/maintaining.texi
>> index aca29910b7d3..8f31fa168c23 100644
>> --- a/doc/emacs/maintaining.texi
>> +++ b/doc/emacs/maintaining.texi
>
> This should go to the ELisp manual, not the Emacs User manual.
>

I don't know how to resolve this issue: there seems no proper place to
insert the defun section. I'm gonna leave my updated version of the
defun section here in this email, and updated all other parts in the new
version of the patch (as attached). You may decide where to put this part.

--------------------- vc-responsible-backend defun -------------------------
@defun vc-responsible-backend file
This function can be used to determine the responsible VC backend of
the given @var{file}.  For example, if @file{emacs.c} is a file
tracked by git, @code{(vc-responsible-backend "emacs.c")} returns
@samp{Git}.  Note that if @var{file} is a symbolic link,
@code{vc-responsible-backend} will not resolve it---the backend of the
symbolic link file itself is reported.  Instead, to get the backend VC
of the file to which @var{file} refers, wrap @var{file} with a
symbolic link resolving function such as @code{file-chase-links}:

@smallexample
(vc-responsible-backend (file-chase-links "emacs.c"))
@end smallexample
@end defun
--------------------- vc-responsible-backend defun ENDS---------------------

> Last, but not least: documentation changes need ChangeLog-style commit
> log messages as well (just use "C-x 4 a" to get a preformatted
> skeleton from which you could start).

Fixed in the new patch. The new version now also mentions
`vc-responsible-backend' in a different way in maintaining.texi. Feel
free to review again. Thanks!