Comment 1 for bug 181399

After setting debug-on-quit, I got a backtrace, printed below (sorry, I had trouble copying the special characters in the line which starts with "byte-code").

I've attached the contents of the Tramp debug buffer with `tramp-verbose' set to 6.

Workaround: everything works if I set `tramp-methods' (net/tramp.el) so that sudo uses "/bin/bash --norc" rather than "/bin/sh". It appears that Tramp is doing things that work in bash but not in dash.

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Backtrace:

Debugger entered--Lisp error: (quit)
  accept-process-output(#<process *tramp/sudo <email address hidden>*> 1 nil)
  byte-code("..." [timeout with-timeout-tag with-timeout-timer with-timeout-timers proc timeout-msecs run-with-timer 1 nil with-timeout-handler accept-process-output with-timeout-value] 6)
  tramp-accept-process-output(#<process *tramp/sudo <email address hidden>*> 1)
  tramp-wait-for-regexp(#<process *tramp/sudo <email address hidden>*> nil "^[^$\n]*///c73bab5635304c1f929c0ec3ee7e6764
?$")
  tramp-wait-for-output(#<process *tramp/sudo <email address hidden>*>)
  tramp-send-command(["sudo" "root" "phil.mit.edu" "/etc/apt/sources.list"] "PROMPT_COMMAND=''; PS1='\n///c73bab5635304c1f929c0ec3ee7e6764\n'; PS2=''; PS3=''" t)
  tramp-open-connection-setup-interactive-shell(#<process *tramp/sudo <email address hidden>*> ["sudo" "root" "phil.mit.edu" "/etc/apt/sources.list"])
  tramp-maybe-open-connection(["sudo" "root" "phil.mit.edu" "/etc/apt/sources.list"])
  tramp-send-command(["sudo" "root" "phil.mit.edu" "/etc/apt/sources.list"] "test 0 2>/dev/null; echo tramp_exit_status $? ")
  tramp-send-command-and-check(["sudo" "root" "phil.mit.edu" "/etc/apt/sources.list"] "test 0")
  tramp-get-test-command(["sudo" "root" "phil.mit.edu" "/etc/apt/sources.list"])
  tramp-run-test("-d" "/sudo:<email address hidden>:/etc/apt/sources.list")
  tramp-handle-file-directory-p("/sudo:<email address hidden>:/etc/apt/sources.list")
  apply(tramp-handle-file-directory-p "/sudo:<email address hidden>:/etc/apt/sources.list")
  tramp-sh-file-name-handler(file-directory-p "/sudo:<email address hidden>:/etc/apt/sources.list")
  apply(tramp-sh-file-name-handler file-directory-p "/sudo:<email address hidden>:/etc/apt/sources.list")
  tramp-file-name-handler(file-directory-p "/sudo:<email address hidden>:/etc/apt/sources.list")
  file-directory-p("/sudo:<email address hidden>:/etc/apt/sources.list")
  find-file-noselect("/sudo::/etc/apt/sources.list" nil nil t)
  find-file("/sudo::/etc/apt/sources.list" t)
  call-interactively(find-file)