bug#3926: 23.1.50; Follow-mode makes Emacs server unavailable

[Dan Nicolaescu <dann@ics.uci.edu>]

Teemu Likonen <tlikonen@iki.fi> writes:

  > When follow-mode is activated Emacs server is no longer available for
  > clients. The server has to be restarted. To reproduce:
  > 
  >  1. Start Emacs:
  >     
  >         emacs -Q -f server-start -f follow-mode
  > 
  >     You probably need to close other Emacs servers first.
  > 
  >  2. Try to start a client session:
  > 
  >         emacsclient -c -n
  > 
  > The emacsclient command just waits and waits but nothing happens. The
  > server must be restarted (M-x server-start) before it starts accepting
  > clients again.

This is a problem in emacs-22 too, with the difference that there
"emacsclient /tmp/test.c" prints an error:
-error Unknown&_command:&_/tmp/test.c

The problem is somewhere in the `set-process-filter' defadvice.  Doing:

emacs -Q -f server-start --eval '(setq follow-intercept-processes nil)' -f follow-mode

makes emacsclient work.

Which is yet another reason not to like defadvice in the emacs sources...