bug#55310: 27.2; vc-revert: unhelpful error message when modified buffers exist

[Alfred M. Szmidt]

When doing vc-revert in a vc-dir buffer, and when one has a bunch of
open files, one somtimes gets the unhelpful message:

  vc-revert: Please kill or save all modified buffers before reverting

Nicer would be prompting the user to kill/save those buffers, or list them.


In GNU Emacs 27.2 (build 1, x86_64-unknown-openbsd, GTK+ Version 3.24.33)
 of 2022-04-09 built on amd64.ports.openbsd.org
System Description: OpenBSD nitrogenium.mendeleev 7.1 GENERIC.MP#465 amd64

Recent messages:
  INFO     Scraping files for loaddefs.el...done
Loading /home/ams/loaddefs.el (source)...done
Loading /home/ams/quicklisp/slime-helper.el (source)...done
Loading /home/ams/quicklisp/clhs-use-local.el (source)...done
Loading /home/ams/private/emacs-nitrogenium.mendeleev...done
For information about GNU Emacs and the GNU system, type C-h C-a.

Configured using:
 'configure --build=amd64-unknown-openbsd --without-sound
 --with-x-toolkit=gtk3 --prefix=/usr/local --sysconfdir=/etc
 --mandir=/usr/local/man --infodir=/usr/local/info
 --localstatedir=/var --disable-silent-rules --disable-gtk-doc
 'CFLAGS=-O2 -pipe -g' CPPFLAGS=-I/usr/local/include
 'LDFLAGS=-L/usr/local/lib -g''

Configured features:
XPM JPEG TIFF GIF PNG RSVG DBUS GSETTINGS GLIB NOTIFY KQUEUE GNUTLS
LIBXML2 FREETYPE HARFBUZZ M17N_FLT LIBOTF XFT ZLIB TOOLKIT_SCROLL_BARS
GTK3 X11 XDBE XIM MODULES THREADS JSON PDUMPER LCMS2 GMP

Important settings:
  locale-coding-system: nil

Major mode: Fundamental

Minor modes in effect:
  global-company-mode: t
  tooltip-mode: t
  global-eldoc-mode: t
  electric-indent-mode: t
  mouse-wheel-mode: t
  tool-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  buffer-read-only: t
  transient-mark-mode: t

Load-path shadows:
~/loaddefs hides /usr/local/share/emacs/27.2/lisp/loaddefs

Features:
(shadow mailalias emacsbug message rmc puny dired dired-loaddefs
format-spec rfc822 mml mml-sec epa epg epg-config gnus-util rmail
rmail-loaddefs text-property-search mm-decode mm-bodies mm-encode
mail-parse rfc2231 mailabbrev gmm-utils mailheader term/screen
term/xterm xterm rcirc time-date mail-queue sendmail rfc2047 rfc2045
ietf-drums mm-util mail-prsvr mail-utils slime-asdf grep
slime-quicklisp slime-fancy slime-indentation slime-cl-indent
cl-indent slime-trace-dialog slime-fontifying-fu slime-package-fu
slime-references slime-compiler-notes-tree slime-scratch
slime-presentations advice bridge slime-macrostep macrostep
slime-mdot-fu slime-enclosing-context slime-fuzzy slime-fancy-trace
slime-fancy-inspector slime-c-p-c slime-editing-commands slime-autodoc
slime-repl elp slime-parse slime derived cl-extra help-mode gud
apropos compile arc-mode archive-mode noutline outline easy-mmode pp
comint ansi-color hyperspec thingatpt slime-autoloads company-oddmuse
company-keywords company-etags etags fileloop generator xref project
ring company-gtags company-dabbrev-code company-dabbrev company-files
company-capf company-cmake company-xcode company-clang
company-semantic company-eclim company-template company-bbdb company
edmacro kmacro pcase cal-menu calendar cal-loaddefs autoload
radix-tree lisp-mnt finder-inf disp-table package easymenu browse-url
url-handlers url-parse auth-source cl-seq eieio eieio-core cl-macs
eieio-loaddefs password-cache json subr-x map url-vars seq byte-opt gv
bytecomp byte-compile cconv cl-loaddefs cl-lib tooltip eldoc electric
uniquify ediff-hook vc-hooks lisp-float-type mwheel term/x-win x-win
term/common-win x-dnd tool-bar dnd fontset image regexp-opt fringe
tabulated-list replace newcomment text-mode elisp-mode lisp-mode
prog-mode register page tab-bar menu-bar rfn-eshadow isearch timer
select scroll-bar mouse jit-lock font-lock syntax facemenu font-core
term/tty-colors frame minibuffer cl-generic cham georgian utf-8-lang
misc-lang vietnamese tibetan thai tai-viet lao korean japanese
eucjp-ms cp51932 hebrew greek romanian slovak czech european ethiopic
indian cyrillic chinese composite charscript charprop case-table
epa-hook jka-cmpr-hook help simple abbrev obarray cl-preloaded nadvice
loaddefs button faces cus-face macroexp files text-properties overlay
sha1 md5 base64 format env code-pages mule custom widget
hashtable-print-readable backquote threads dbusbind kqueue lcms2
dynamic-setting system-font-setting font-render-setting move-toolbar
gtk x-toolkit x multi-tty make-network-process emacs)

Memory information:
((conses 16 190926 10037)
 (symbols 48 15424 2)
 (strings 32 47013 758)
 (string-bytes 1 1409610)
 (vectors 16 17009)
 (vector-slots 8 200499 8642)
 (floats 8 62 187)
 (intervals 56 260 129)
 (buffers 1000 12))