bug#28495: 25.2; follow.el; Missing lighter and unused variable

[Duncan Harvey]

In .../lisp/follow.el{.gz} `follow-mode-line-text' is defined but not used.  
Also, the `follow-mode' minor-mode does not define a lighter.

My expectations, in order of preference:

1) Use the variable to define a lighter for `follow-mode', e.g.:

--- follow.el   2017-02-03 10:25:44.000000000 +0000
+++ enlightened-follow.el       2017-09-18 14:53:15.000000000 +0100
@@ -416,6 +416,7 @@ (define-minor-mode follow-mode

Keys specific to Follow mode:
\\{follow-mode-map}"
+  :lighter follow-mode-line-text
   :keymap follow-mode-map
   (if follow-mode
       (progn

2) Define a lighter for `follow-mode', but don't use `follow-mode-line-text'; 
remove definition of `follow-mode-line-text'.

3) Leave `follow-mode' without a lighter; remove definition of 
`follow-mode-line-text'.


In GNU Emacs 25.2.1 (x86_64-apple-darwin13.4.0, NS appkit-1265.21 Version 
10.9.5 (Build 13F1911))
of 2017-04-21 built on builder10-9.porkrind.org
Windowing system distributor 'Apple', version 10.3.1504
Configured using:
'configure --with-ns '--enable-locallisppath=/Library/Application
Support/Emacs/${version}/site-lisp:/Library/Application
Support/Emacs/site-lisp' --with-modules'

Configured features:
NOTIFY ACL GNUTLS LIBXML2 ZLIB TOOLKIT_SCROLL_BARS NS MODULES

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

Major mode: Lisp Interaction

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
  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.

Load-path shadows:
None found.

Features:
(shadow sort mail-extr emacsbug message dired format-spec rfc822 mml
mml-sec password-cache epg epg-config gnus-util mm-decode mm-bodies
mm-encode mail-parse rfc2231 mailabbrev gmm-utils mailheader sendmail
rfc2047 rfc2045 ietf-drums 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 ns-win ucs-normalize term/common-win 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 kqueue cocoa ns multi-tty
make-network-process emacs)

Memory information:
((conses 16 195592 8052)
(symbols 48 19499 0)
(miscs 40 51 194)
(strings 32 14879 5891)
(string-bytes 1 430402)
(vectors 16 32840)
(vector-slots 8 649625 4411)
(floats 8 160 47)
(intervals 56 199 0)
(buffers 976 18))