bug#21555: 25.0.50; per-project *vc-change-log* buffers

[Tom Tromey]

I often work on several projects at once, using a *vc-dir* buffer for
each.

If I type "l" in this buffer, I get a *vc-change-log* buffer with the
history of the project.

However, all calls to vc-print-log use this same buffer.
This seems to be hard-coded in vc.el (vc-print-log-internal).

I would like to be able to make it so that each use of "l" from a
*vc-dir* buffer gets its own *vc-change-log* buffer; and that "C-x v l"
in some source file gets a separate buffer.  This way the per-project
change-log buffers could be relatively long-lived; as it is recomputing
the data in them takes much too long.




In GNU Emacs 25.0.50.5 (x86_64-unknown-linux-gnu, GTK+ Version 3.16.6)
 of 2015-08-18 on pokyo
Repository revision: 78284d534ba7c17c3b5d9d6d1e538277546f8159
Windowing system distributor `Fedora Project', version 11.0.11702000
Configured using:
 `configure --prefix=/home/tromey/Emacs/install/
 --with-file-notification=no'

Configured features:
XPM JPEG TIFF GIF PNG RSVG IMAGEMAGICK SOUND DBUS GCONF GSETTINGS
LIBSELINUX GNUTLS LIBXML2 FREETYPE LIBOTF XFT ZLIB TOOLKIT_SCROLL_BARS
GTK3 X11

Important settings:
  value of $LANG: en_US.UTF-8
  value of $XMODIFIERS: @im=ibus
  locale-coding-system: utf-8-unix

Major mode: Emacs-Lisp

Minor modes in effect:
  async-bytecomp-package-mode: t
  shell-dirtrack-mode: t
  erc-spelling-mode: t
  erc-truncate-mode: t
  diff-auto-refine-mode: t
  flyspell-mode: t
  which-function-mode: t
  projectile-global-mode: t
  projectile-mode: t
  erc-notify-mode: t
  erc-notifications-mode: t
  erc-services-mode: t
  erc-list-mode: t
  erc-menu-mode: t
  erc-autojoin-mode: t
  erc-ring-mode: t
  erc-networks-mode: t
  erc-pcomplete-mode: t
  erc-track-mode: t
  erc-track-minor-mode: t
  erc-match-mode: t
  erc-netsplit-mode: t
  erc-hl-nicks-mode: t
  erc-button-mode: t
  erc-fill-mode: t
  erc-stamp-mode: t
  erc-irccontrols-mode: t
  erc-noncommands-mode: t
  erc-move-to-prompt-mode: t
  erc-readonly-mode: t
  savehist-mode: t
  tooltip-mode: t
  global-eldoc-mode: t
  eldoc-mode: t
  electric-indent-mode: t
  mouse-wheel-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  column-number-mode: t
  line-number-mode: t
  auto-fill-function: do-auto-fill
  transient-mark-mode: t

Recent messages:
Saving file 
/home/tromey/firefox-git/gecko-dev/.git/rebase-merge/git-rebase-todo...
Wrote /home/tromey/firefox-git/gecko-dev/.git/rebase-merge/git-rebase-todo
Mark set
C-x C-g is undefined
Mark saved where search started
Making completion list...
Finding changes in /home/tromey/firefox-git/gecko-dev/...
Type C-x 1 to delete the help window.
uncompressing vc.el.gz...done
Mark saved where search started

Load-path shadows:
/home/tromey/.emacs.d/elpa/bubbles-0.5/bubbles hides 
/home/tromey/Emacs/install/share/emacs/25.0.50/lisp/play/bubbles

Features:
(shadow emacsbug arc-mode archive-mode calc-aent calc-menu calc-embed
calc-ext calc calc-loaddefs calc-macs tramp-cache tabify man compare-w
iso-transl perl-mode gamegrid recentf tree-widget with-editor
async-bytecomp term ehelp esh-var esh-io esh-cmd esh-opt esh-ext
esh-proc esh-arg esh-groups eshell esh-module esh-mode esh-util async
tar-mode cus-edit url-handlers disass gud autoload lisp-mnt hi-lock
etags dired-aux vc-annotate ffap rect css-mode eww url-queue python
tramp-sh tramp tramp-compat tramp-loaddefs trampver shell webjump xref
project thai-util thai-word mailalias bbdb-sc supercite regi mail-hist
nnir gnus-fun find-dired url-http url-gw url-auth epg conf-mode
gnus-draft ido nxml-uchnm rng-xsd xsd-regexp rng-cmpct rng-nxml
rng-valid rng-loc rng-uri rng-parse nxml-parse rng-match rng-dt rng-util
rng-pttrn nxml-ns nxml-mode nxml-outln nxml-rap nxml-util nxml-glyph
nxml-enc xmltok eieio-opt speedbar sb-image ezimage dframe gnus-html
url-cache mm-url url url-proxy url-privacy url-expand url-methods
url-history url-cookie url-domsuf flow-fill bbdb-gui bbdb-hooks
bbdb-rmail rmailsum rmail sort gnus-cite smiley shr-color url-util
url-parse url-vars shr dom mm-archive gnus-async gnus-bcklg qp gnus-ml
disp-table gnus-topic nndraft nnmh nnfolder utf-7 bbdb-gnus bbdb-snarf
mail-extr bbdb-com warnings gnus-agent gnus-srvr gnus-score score-mode
nnvirtual gnus-msg nntp gnus-cache gnus-registry registry eieio-compat
eieio-base gnus-art mm-uu mml2015 mm-view mml-smime smime dig mailcap
gnus-sum gnus-group gnus-undo smtpmail sendmail gnus-start gnus-cloud
nnimap nnmail mail-source utf7 netrc nnoo parse-time gnus-spec gnus-int
gnus-range gnus-win gnus gnus-ems nnheader org-element org-rmail org-mhe
org-irc org-info org-gnus org-docview doc-view image-mode org-bibtex
bibtex org-bbdb org-w3m org org-macro org-footnote org-pcomplete
org-list org-faces org-entities noutline outline org-version
ob-emacs-lisp ob ob-tangle ob-ref ob-lob ob-table ob-exp org-src ob-keys
ob-comint ob-core ob-eval org-compat org-macs org-loaddefs dxr
browse-url find-file idutils sgml-mode vc-mtn vc-hg gnutls
network-stream nsm starttls tls erc-spelling erc-truncate
git-commit-mode log-edit message dired rfc822 mml mml-sec mm-decode
mm-bodies mm-encode mail-parse rfc2231 rfc2047 rfc2045 ietf-drums
mailabbrev mail-utils gmm-utils mailheader dabbrev smerge-mode copyright
git-rebase-mode term/xterm xterm misearch multi-isearch js json cc-mode
cc-fonts cc-guess cc-menus cc-cmds grep bug-reference add-log log-view
pcvs-util vc-git diff-mode vc-bzr vc-src vc-sccs vc-svn vc-cvs vc-rcs
flyspell ispell diminish appt diary-lib diary-loaddefs cal-menu calendar
cal-loaddefs which-func imenu projectile ibuf-macs ibuf-ext ibuffer
minimap autorevert filenotify desktop frameset cus-start cus-load
erc-notify erc-desktop-notifications notifications dbus xml erc-services
erc-list erc-menu erc-join erc-ring erc-networks erc-pcomplete pcomplete
erc-track erc-match erc-netsplit erc-hl-nicks color erc-button erc-fill
erc-stamp wid-edit erc-goodies erc erc-backend erc-compat format-spec
auth-source eieio byte-opt bytecomp byte-compile cl-extra seq cconv
gnus-util mm-util help-fns mail-prsvr password-cache thingatpt pp status
advice vc-dir ewoc vc vc-dispatcher flycheck derived easy-mmode cl-seq
edmacro kmacro find-func help-mode rx subr-x dash jka-compr sh-script
smie executable compile let-alist cc-styles cc-align cc-engine cc-vars
cc-defs bbdb cl timezone ange-ftp comint ansi-color ring server savehist
finder-inf bbdb-autoloads dwarf-mode-autoloads eieio-core cl-macs gv
cl-loaddefs pcase cl-lib lisppaste-autoloads pydoc-info-autoloads
info-look info weblogger-autoloads package easymenu epg-config time-date
mule-util tooltip eldoc electric uniquify ediff-hook vc-hooks
lisp-float-type mwheel x-win term/common-win x-dnd tool-bar dnd fontset
image regexp-opt fringe tabulated-list newcomment elisp-mode lisp-mode
prog-mode register page menu-bar rfn-eshadow timer select scroll-bar
mouse jit-lock font-lock syntax facemenu font-core frame 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 charscript case-table epa-hook
jka-cmpr-hook help simple abbrev minibuffer 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 dbusbind dynamic-setting
system-font-setting font-render-setting move-toolbar gtk x-toolkit x
multi-tty make-network-process emacs)

Memory information:
((conses 16 3011681 859506)
 (symbols 48 132351 1487)
 (miscs 40 29224 21152)
 (strings 32 816797 269877)
 (string-bytes 1 34115078)
 (vectors 16 214055)
 (vector-slots 8 4461660 211249)
 (floats 8 1265 3664)
 (intervals 56 134269 106424)
 (buffers 976 1018)
 (heap 1024 439477 770948))

Tom