bug#23322: 25.0.92; Tramp and find-file error

[Live System User]

Hi,

In my Emacs environment using Tramp to access a file using the
ssh method, I get the following backtrace (see below) with
C-x C-f `(find-file)':

        Find file: ~//ssh:localhost:~/xpra.test

`(list-process)' yields:

*tramp/ssh l... run     *tramp/ssh l... /dev/pts/14  /bin/sh -i

However, immediately executing the same command `(find-file)' again,
I successfully get new buffer for the file:

.%  *Process List*           64 Process Menu     
    ssh:xpra.test             0 Fundamental      
/ssh:localhost:/home/liveuser/xpra.test
  * l                      3676 Fundamental      
 %* *Backtrace*            3676 Debugger         
    *scratch*               145 Lisp Interaction 
 %* *Messages*             2479 Messages         
  * *tramp/ssh local...       0 Fundamental      


Does the *Backtrace* reveal any clues on what went initially wrong?

How do I debug this?

Thanks.

Debugger entered--Lisp error: (wrong-type-argument processp nil)
  signal(wrong-type-argument (processp nil))
  completion--some(#[257 "\303\302\300\301$\207" ["/ssh:localhost:~/xpra.test" 
file-exists-p lambda complete-with-action] 6 "\n\n(fn TABLE)"] 
(completion--embedded-envvar-table completion--file-name-table))
  read-file-name-internal("/ssh:localhost:~/xpra.test" file-exists-p lambda)
  test-completion("/ssh:localhost:~/xpra.test" read-file-name-internal 
file-exists-p)
  completion--complete-and-exit(12 38 exit-minibuffer #[0 
"\3041\305\300\301\306\307$0\202\210\310\211\311>\203\302 \2023\211\312=\2032
\204*\302 \2023\313\314!\210\306\2023\306\207" [12 38 exit-minibuffer 
minibuffer-completion-confirm (error) completion--do-completion nil 
expect-exact 1 (3 1) 7 minibuffer-message "Confirm"] 5])
  completion-complete-and-exit(12 38 exit-minibuffer)
  minibuffer-complete-and-exit()
  funcall-interactively(minibuffer-complete-and-exit)
  call-interactively(minibuffer-complete-and-exit nil nil)
  command-execute(minibuffer-complete-and-exit)
  read-from-minibuffer("Find file: " "~/" (keymap (keymap (32)) keymap (10 . 
minibuffer-complete-and-exit) (13 . minibuffer-complete-and-exit) keymap 
(menu-bar keymap (minibuf "Minibuf" keymap (tab menu-item "Complete" 
minibuffer-complete :help "Complete as far as possible") (space menu-item 
"Complete Word" minibuffer-complete-word :help "Complete at most one word") (63 
menu-item "List Completions" minibuffer-completion-help :help "Display all 
possible completions") "Minibuf")) (27 keymap (118 . switch-to-completions)) 
(prior . switch-to-completions) (63 . minibuffer-completion-help) (32 . 
minibuffer-complete-word) (9 . minibuffer-complete) keymap (menu-bar keymap 
(minibuf "Minibuf" keymap (previous menu-item "Previous History Item" 
previous-history-element :help "Put previous minibuffer history element in the 
minibuffer") (next menu-item "Next History Item" next-history-element :help 
"Put next minibuffer history element in the minibuffer") (isearch-backward 
menu-item "Isearch History Backward" isearch-backward :help "Incrementally 
search minibuffer history backward") (isearch-forward menu-item "Isearch 
History Forward" isearch-forward :help "Incrementally search minibuffer history 
forward") (return menu-item "Enter" exit-minibuffer :key-sequence "" :help 
"Terminate input and exit minibuffer") (quit menu-item "Quit" 
abort-recursive-edit :help "Abort input and exit minibuffer") "Minibuf")) (10 . 
exit-minibuffer) (13 . exit-minibuffer) (7 . abort-recursive-edit) (C-tab . 
file-cache-minibuffer-complete) (9 . self-insert-command) (XF86Back . 
previous-history-element) (up . previous-line-or-history-element) (prior . 
previous-history-element) (XF86Forward . next-history-element) (down . 
next-line-or-history-element) (next . next-history-element) (27 keymap (114 . 
previous-matching-history-element) (115 . next-matching-history-element) (112 . 
previous-history-element) (110 . next-history-element))) nil file-name-history 
"~/" nil)
  completing-read-default("Find file: " read-file-name-internal file-exists-p 
confirm-after-completion "~/" file-name-history "~/" nil)
  completing-read("Find file: " read-file-name-internal file-exists-p 
confirm-after-completion "~/" file-name-history "~/")
  read-file-name-default("Find file: " nil "~/" confirm-after-completion nil 
nil)
  read-file-name("Find file: " nil "~/" confirm-after-completion)
  find-file-read-args("Find file: " confirm-after-completion)
  byte-code("\300\301\302 \"\207" [find-file-read-args "Find file: " 
confirm-nonexistent-file-or-buffer] 3)
  call-interactively(find-file nil nil)
  command-execute(find-file)




In GNU Emacs 25.0.92.1 (x86_64-redhat-linux-gnu, GTK+ Version 3.18.7)
 of 2016-03-03 built on copr-builder-919644472.novalocal
Windowing system distributor 'Fedora Project', version 11.0.11799901
Configured using:
 'configure --build=x86_64-redhat-linux-gnu
 --host=x86_64-redhat-linux-gnu --program-prefix=
 --disable-dependency-tracking --prefix=/usr --exec-prefix=/usr
 --bindir=/usr/bin --sbindir=/usr/sbin --sysconfdir=/etc
 --datadir=/usr/share --includedir=/usr/include --libdir=/usr/lib64
 --libexecdir=/usr/libexec --localstatedir=/var
 --sharedstatedir=/var/lib --mandir=/usr/share/man
 --infodir=/usr/share/info --with-dbus --with-gif --with-jpeg --with-png
 --with-rsvg --with-tiff --with-xft --with-xpm --with-x-toolkit=gtk3
 --with-gpm=no build_alias=x86_64-redhat-linux-gnu
 host_alias=x86_64-redhat-linux-gnu 'CFLAGS=-DMAIL_USE_LOCKF -O2 -g
 -pipe -Wall -Werror=format-security -Wp,-D_FORTIFY_SOURCE=2
 -fexceptions -fstack-protector-strong --param=ssp-buffer-size=4
 -grecord-gcc-switches -specs=/usr/lib/rpm/redhat/redhat-hardened-cc1
 -m64 -mtune=generic' LDFLAGS=-Wl,-z,relro
 PKG_CONFIG_PATH=:/usr/lib64/pkgconfig:/usr/share/pkgconfig'

Configured features:
XPM JPEG TIFF GIF PNG RSVG IMAGEMAGICK SOUND DBUS GCONF GSETTINGS NOTIFY
ACL LIBSELINUX GNUTLS LIBXML2 FREETYPE M17N_FLT 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: Fundamental

Minor modes in effect:
  tooltip-mode: t
  global-eldoc-mode: t
  electric-indent-mode: t
  mouse-wheel-mode: t
  tool-bar-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  blink-cursor-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  line-number-mode: t
  transient-mark-mode: t

Recent messages:
For information about GNU Emacs and the GNU system, type C-h C-a.
Mark set
("~/.emacs.d/lisp" "/usr/share/emacs/25.0.92/site-lisp" 
"/usr/share/emacs/site-lisp" "/usr/share/emacs/site-lisp/desktop-file-utils" 
"/usr/share/emacs/site-lisp/git" "/usr/share/emacs/site-lisp/libidn" 
"/usr/share/emacs/site-lisp/site-start.d" "/usr/share/emacs/25.0.92/lisp" 
"/usr/share/emacs/25.0.92/lisp/vc" "/usr/share/emacs/25.0.92/lisp/url" 
"/usr/share/emacs/25.0.92/lisp/textmodes" 
"/usr/share/emacs/25.0.92/lisp/progmodes" ...)
Making completion list...
Mark set
Will sendmail by aol
‘epa-file’ already enabled
Making completion list...

Load-path shadows:
~/.emacs.d/lisp/ntlm hides /usr/share/emacs/25.0.92/lisp/net/ntlm

Features:
(shadow sort mail-extr emacsbug sendmail epa-file epa derived
auth-source cl-seq eieio byte-opt bytecomp byte-compile cl-extra cconv
eieio-core cl-macs gv sieve sieve-mode sieve-manage password-cache nnir
gnus-sum gnus-group gnus-undo gnus-start gnus-cloud nnimap nnmail
mail-source tls gnutls utf7 netrc parse-time gnus-spec gnus-int
gnus-range message idna dired format-spec rfc822 mml mml-sec epg
epg-config mm-decode mm-bodies mm-encode mail-parse rfc2231 rfc2047
rfc2045 ietf-drums mailabbrev gmm-utils mailheader gnus-win gnus
gnus-ems wid-edit nnoo nnheader gnus-util mm-util help-fns help-mode
easymenu cl-loaddefs pcase cl-lib mail-prsvr mail-utils 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 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 136166 9635)
 (symbols 48 25650 0)
 (miscs 40 48 126)
 (strings 32 30467 3695)
 (string-bytes 1 977975)
 (vectors 16 18551)
 (vector-slots 8 491117 8023)
 (floats 8 295 192)
 (intervals 56 277 0)
 (buffers 976 14)
 (heap 1024 35170 1107))