bug#26950: 26.0.50; ERC doesn't use auth-source for NickServ password

[Tom Tromey <tom@tromey.com>]

ERC uses erc-nickserv-passwords to store passwords used for
authenticating to NickServ.  It would be nice if it could also use
auth-source to get this information, so I could store my NickServ
passwords elsewhere.


In GNU Emacs 26.0.50 (build 3, x86_64-pc-linux-gnu, GTK+ Version 3.22.10)
 of 2017-04-03 built on pokyo
Repository revision: f33d65cecbb4a98251b1deb7c05ff9c3f5e2eadb
Windowing system distributor 'Fedora Project', version 11.0.11903000
System Description:	Fedora release 25 (Twenty Five)

Recent messages:
File lisp/erc/erc-menu.el added to project /home/tromey/Emacs/emacs/ cache.
Mark saved where search started
Grep finished (matches found)
Making completion list...
Quit
Grep finished (matches found)
scroll-up-command: End of buffer
scroll-down-command: Beginning of buffer
Mark saved where search started [4 times]
C-x C-g is undefined
Quit [2 times]
Configured using:
 'configure --prefix=/home/tromey/Emacs/install --with-modules'

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

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:
  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

Load-path shadows:
/home/tromey/.emacs.d/elpa/bubbles-0.5/bubbles hides /home/tromey/Emacs/install/share/emacs/26.0.50/lisp/play/bubbles

Features:
(shadow emacsbug arc-mode archive-mode thai-util thai-word wtf goto-addr
face-remap ido macros webjump pcmpl-unix pcmpl-gnu iso-transl
cursor-sensor mhtml-mode make-mode apropos 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-enc xmltok css-mode eww git-rebase-mode org-bullets etags xref
project rst ix grapnel gnus-draft gud find-file conf-mode gdb-shell
find-dired git-commit-mode log-edit term/xterm xterm compare-w novice
cl-print edebug rust-mode binhex eieio-opt speedbar sb-image ezimage
dframe smerge-mode log-view pcvs-util vc-annotate dxr m4-mode autoconf
autoconf-mode python tramp-sh tramp tramp-compat tramp-loaddefs trampver
ucs-normalize shell ffap idutils dabbrev mailalias bbdb-sc supercite
regi mail-hist nnir copyright sh-script smie executable gnus-fun
org-element org-rmail org-mhe org-irc org-info org-gnus org-docview
doc-view jka-compr 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 add-log bug-reference js sgml-mode cc-mode
cc-fonts cc-guess cc-menus cc-cmds gnus-html url-queue help-fns
radix-tree url-cache mm-url misearch multi-isearch erc-spelling
erc-truncate url-http url url-proxy url-privacy url-history url-auth
url-cookie url-domsuf url-gw url-expand url-methods shr-color url-util
shr svg dom browse-url bbdb-gui bbdb-hooks bbdb-rmail rmailsum vc-mtn
vc-hg vc-git diff-mode vc-bzr vc-src vc-sccs vc-svn vc-cvs vc-rcs sort
smiley gnus-cite flow-fill 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 network-stream nsm starttls gnus-agent gnus-srvr
gnus-score score-mode nnvirtual gnus-msg nntp gnus-cache gnus-registry
registry 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 tls gnutls utf7 netrc nnoo
parse-time gnus-spec gnus-int gnus-range message puny rfc822 mml mml-sec
epa derived epg mm-decode mm-bodies mm-encode mail-parse rfc2231
mailabbrev gmm-utils mailheader gnus-win gnus nnheader gnus-util rmail
rmail-loaddefs rfc2047 rfc2045 ietf-drums mail-utils mm-util mail-prsvr
flyspell ispell diminish appt diary-lib diary-loaddefs cal-menu calendar
cal-loaddefs which-func imenu edmacro kmacro projectile grep compile
ibuf-ext ibuffer ibuffer-loaddefs autorevert filenotify desktop frameset
cus-start cus-load erc-notify erc-desktop-notifications erc-services
notifications dbus xml erc-list erc-menu erc-join erc-ring erc-networks
erc-pcomplete pcomplete erc-track erc-match erc-netsplit erc-hl-nicks
easy-mmode color erc-button erc-fill erc-stamp wid-edit erc-goodies erc
erc-backend erc-compat format-spec thingatpt pp dired-aux dired-x dired
dired-loaddefs warnings advice vc-dir ewoc vc vc-dispatcher flycheck
json map find-func rx dash 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 lisppaste-autoloads
pydoc-info-autoloads info-look weblogger-autoloads info package
epg-config url-handlers url-parse auth-source cl-seq eieio eieio-core
cl-macs eieio-loaddefs password-cache url-vars seq byte-opt subr-x gv
bytecomp byte-compile cl-extra help-mode easymenu cconv cl-loaddefs
pcase cl-lib time-date mule-util 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 menu-bar rfn-eshadow isearch timer select
scroll-bar mouse jit-lock font-lock syntax facemenu font-core
term/tty-colors 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 composite charscript case-table epa-hook jka-cmpr-hook help
simple abbrev obarray 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 inotify dynamic-setting system-font-setting
font-render-setting move-toolbar gtk x-toolkit x multi-tty
make-network-process emacs)

Memory information:
((conses 16 8385849 3639969)
 (symbols 48 166679 188)
 (miscs 40 65331 52558)
 (strings 32 1615920 1471618)
 (string-bytes 1 75405070)
 (vectors 16 353248)
 (vector-slots 8 8369725 421965)
 (floats 8 1026 4538)
 (intervals 56 801540 13193)
 (buffers 976 1695))

Tom