When visiting a file with tramp and killing text with xclip-mode
enabled, the text gets sent to the kill-ring but the X clipboard does
not get set. Additionally, the xclip shell process does not close.

Steps to reproduce:

-   Ensure xclip is installed (In the shell: `which xclip`)
-   Install xclip Emacs package
-   Set variables `x-select-enable-clipboard` and/or
`x-select-enable-primary` to `t`.
-   Enable xclip (`M-x xclip-mode RET`)
-   Visit a file using tramp (eg. `/sudo:user@localhost:/tmp/tramp-file`)
-   Type some text
-   Select a region and kill it

Expected behaviour

-   Selected text gets sent to the kill-ring and X clipboard or primary
    buffer (this can be verified in the shell with `xclip -o -selection
primary` and/or
    `xclip -o -selection clipboard`.
-   xclip processes exit cleanly

Observed behaviour

-   Selected text gets sent to the kill-ring, but not the X clipboard or
    primary buffers.
-   xclip processes do not terminate (user is warned that they are still
    running when exiting Emacs).
-   Further, yanking text at this point causes the contents of the X
    clipboard or primary buffer to be inserted at the tip of the
    kill-ring so that gets yanked instead of the killed text.

Workarounds

As suggested in Emacs StackExchange by user Stefan
(https://emacs.stackexchange.com/q/45991/7189) replacing
`start-file-process` with `start-process` in a copy of the xclip 1.4
source fixes this particular issue though whether this causes any
unwanted side effects has not been extensively tested.

--

In GNU Emacs 25.2.2 (x86_64-pc-linux-gnu, GTK+ Version 3.23.2)
 of 2018-08-27, modified by Debian built on lgw01-amd64-037
System Description: Ubuntu 18.10

Configured using:
 'configure --build x86_64-linux-gnu --prefix=/usr
 --sharedstatedir=/var/lib --libexecdir=/usr/lib
 --localstatedir=/var/lib --infodir=/usr/share/info
 --mandir=/usr/share/man --with-pop=yes
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 --prefix=/usr --sharedstatedir=/var/lib --libexecdir=/usr/lib
 --localstatedir=/var/lib --infodir=/usr/share/info
 --mandir=/usr/share/man --with-pop=yes
 --enable-locallisppath=/etc/emacs:/usr/local/share/emacs/25.2/site-lisp:/usr/local/share/emacs/site-lisp:/usr/share/emacs/25.2/site-lisp:/usr/share/emacs/site-lisp
 --with-sound=alsa --without-gconf --with-x=yes --with-x-toolkit=gtk3
 --with-toolkit-scroll-bars 'CFLAGS=-g -O2
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-fstack-protector-strong
 -Wformat -Werror=format-security -Wall' 'CPPFLAGS=-Wdate-time
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Configured features:
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ACL LIBSELINUX GNUTLS LIBXML2 FREETYPE M17N_FLT LIBOTF XFT ZLIB
TOOLKIT_SCROLL_BARS GTK3 X11

Important settings:
  value of $LC_COLLATE: C
  value of $LC_MONETARY: en_GB.UTF-8
  value of $LC_NUMERIC: en_GB.UTF-8
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Major mode: Lisp Interaction

Minor modes in effect:
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  line-number-mode: t
  transient-mark-mode: t

Recent messages:
For information about GNU Emacs and the GNU system, type C-h C-a.
Quit
C-x C-g is undefined

Load-path shadows:
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Features:
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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 89350 6746)
 (symbols 48 19877 0)
 (miscs 40 40 121)
 (strings 32 14378 4594)
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