bug#41663: 26.3; ffap-rfc-path requires a method for the latest version of tramp

[Paul Clark]

The default value of ffap-rfc-path, set in
/usr/share/emacs/26.3/lisp/ffap.el.gz, is
"/anonymous@ftp.rfc-editor.org:/in-notes/rfc%s.txt". The method part of
remote file names is now mandatory in tramp (from Emacs 26.1 according
to /usr/share/emacs/26.3/etc/NEWS). ffap-rfc-path needs to be changed to
"/ftp:anonymous@ftp.rfc-editor.org:/in-notes/rfc%s.txt".

Recipe to demonstrate the problem:

Start emacs with "emacs -Q".

Type "RFC6214". Run ffap with "M-x ffap <return>". The minibuffer
contains

    Find file or URL: /anonymous@ftp.rfc-editor.org:/in-notes/rfc6214.txt

with the cursor after the last "/". Pressing "<return>" finds the
nonexistent file "/anonymous@ftp.rfc-editor.org:/in-notes/rfc6214.txt".

To fix:

Go back to *scratch* buffer with "C-x b <return>". Type
"M-x set-variable <return> ffap-rfc-path <return>". Retrieve current
value with "<down>", then "<right> <right> ftp:" so the minibuffer
contains

    Set ffap-rfc-path globally to value 
"/ftp:anonymous@ftp.rfc-editor.org:/in-notes/rfc%s.txt"

Type "<return>". Then run ffap again with "M-x ffap <return>". The minibuffer
contains

    Find file or URL: /ftp:anonymous@ftp.rfc-editor.org:/in-notes/rfc6214.txt

Type "<return>". Emacs loads the correct document.

In GNU Emacs 26.3 (build 1, x86_64-pc-linux-gnu, GTK+ Version 3.24.20)
 of 2020-05-19 built on felixonmars2
Windowing system distributor 'The X.Org Foundation', version 11.0.12008000
Recent messages:
End of search results. [2 times]
C-j runs the command electric-newline-and-maybe-indent
Type "q" in help window to restore its previous buffer, C-M-v to scroll help.
Mark saved where search started
End of search results. [2 times]
Mark set
Type C-x 4 C-o RET to restore the other window.  
Type "q" in help window to restore its previous buffer.

Making completion list...

Configured using:
 'configure --prefix=/usr --sysconfdir=/etc --libexecdir=/usr/lib
 --localstatedir=/var --with-x-toolkit=gtk3 --with-xft --with-wide-int
 --with-modules 'CFLAGS=-march=x86-64 -mtune=generic -O2 -pipe -fno-plt'
 CPPFLAGS=-D_FORTIFY_SOURCE=2
 LDFLAGS=-Wl,-O1,--sort-common,--as-needed,-z,relro,-z,now'

Configured features:
XPM JPEG TIFF GIF PNG RSVG IMAGEMAGICK SOUND GPM DBUS GSETTINGS GLIB
NOTIFY ACL GNUTLS LIBXML2 FREETYPE M17N_FLT LIBOTF XFT ZLIB
TOOLKIT_SCROLL_BARS GTK3 X11 XDBE XIM MODULES THREADS LIBSYSTEMD LCMS2

Important settings:
  value of $LANG: en_GB.UTF-8
  locale-coding-system: utf-8-unix

Major mode: Help

Minor modes in effect:
  diff-auto-refine-mode: t
  electric-pair-mode: t
  recentf-mode: t
  show-paren-mode: t
  tooltip-mode: t
  global-eldoc-mode: t
  electric-indent-mode: t
  mouse-wheel-mode: t
  menu-bar-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
  buffer-read-only: t
  line-number-mode: t
  transient-mark-mode: t

Load-path shadows:
None found.

Features:
(shadow sort mail-extr emacsbug apropos misearch multi-isearch cl-extra
gambit cmuscheme scheme dabbrev network-stream starttls url-http url-gw
nsm url-auth url-queue url-cache url url-proxy url-privacy url-expand
url-methods url-history url-cookie url-domsuf url-util shr svg xml dom
browse-url my-mail sendmail notmuch hl-line notmuch-hello notmuch-tree
notmuch-show notmuch-print notmuch-crypto notmuch-mua notmuch-message
notmuch-draft notmuch-maildir-fcc notmuch-address notmuch-company
notmuch-parser notmuch-wash diff-mode coolj notmuch-query goto-addr
icalendar diary-lib diary-loaddefs notmuch-tag edmacro kmacro crm
notmuch-lib notmuch-version notmuch-compat cl mm-view mml-smime smime
dig mailcap eieio-opt speedbar sb-image ezimage dframe help-fns
radix-tree help-mode flyspell ispell org-rmail org-mhe org-irc org-info
org-gnus nnir gnus-sum gnus-group gnus-undo gnus-start gnus-cloud nnimap
nnmail mail-source tls gnutls utf7 netrc nnoo parse-time gnus-spec
gnus-int gnus-range message rmc puny seq rfc822 mml mml-sec epa derived
epg epg-config 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
org-docview doc-view jka-compr image-mode dired-x dired dired-loaddefs
org-bibtex bibtex org-bbdb org-w3m org-agenda org-element avl-tree
generator my-org org advice org-macro org-footnote org-pcomplete
pcomplete org-list org-faces org-entities noutline outline easy-mmode
org-version ob-emacs-lisp ob ob-tangle org-src ob-ref ob-lob ob-table
ob-keys ob-exp ob-comint comint ansi-color ring ob-core ob-eval
org-compat org-macs org-loaddefs format-spec find-func my-calendar
cal-menu calendar cal-loaddefs server pdf-loader pdf-autoloads elec-pair
windmove ffap thingatpt url-parse auth-source cl-seq eieio byte-opt
bytecomp byte-compile cconv eieio-core cl-macs gv eieio-loaddefs
password-cache url-vars recentf tree-widget wid-edit cl-loaddefs cl-lib
easymenu time-date paren 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
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hebrew greek romanian slovak czech european ethiopic indian cyrillic
chinese composite charscript charprop 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 threads dbusbind inotify 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 289417 36024)
 (symbols 48 37446 1)
 (miscs 40 844 2479)
 (strings 32 86594 4608)
 (string-bytes 1 2681776)
 (vectors 16 40920)
 (vector-slots 8 1473838 160212)
 (floats 8 253 584)
 (intervals 56 2158 419)
 (buffers 992 29))

-- 
Paul Clark