bug#16886: 24.3.50; Lisp nesting exceeds `max-lisp-eval-depth' with `M-x cancel-debug-on-entry'

[Drew Adams <drew.adams@oracle.com>]

Hope this helps.  This was with my setup.  AFAIK, I had used
`debug-on-entry' for only one function.

I then did `M-x cancel-debug-on-entry RET', and Emacs took a
long time to return (used lots of CPU).  I tried it again, and
got the backtrace.

I then did `M-x cancel-debug-on-entry' and instead of
hitting RET I hit TAB.  `nil' appeared as the default for
the function whose debugging is to be canceled.

Both that and the backtrace show that somehow
`debugger-list-functions' is returning the list `(nil)'.
No idea why.  AFAIK, I do not fiddle with any such list of functions
or such advice.

Debugger entered--Lisp error: (error "Lisp nesting exceeds `max-lisp-eval-depth'")
  advice--p(nil)
  advice--member-p(debug--implement-debug-on-entry debug--implement-debug-on-entry nil)
  advice-function-member-p(debug--implement-debug-on-entry nil)
  advice-member-p(debug--implement-debug-on-entry NIKHAHIT)
  #[257 "...
  mapatoms(#[257 "...
  debug--function-list()
  cancel-debug-on-entry(nil)
  mapcar(cancel-debug-on-entry (nil))
<---------------585 repetitions of the last two lines---------------->
  mapcar(cancel-debug-on-entry (nil))
  cancel-debug-on-entry(nil)
  call-interactively(cancel-debug-on-entry record-it)
  icicle-execute-extended-command-1("cancel-debug-on-entry")
  #[nil "...
  call-interactively(icicle-execute-extended-command nil nil)
  command-execute(icicle-execute-extended-command)

In GNU Emacs 24.3.50.1 (i686-pc-mingw32)
 of 2014-02-21 on ODIEONE
Bzr revision: 116523 lekktu@gmail.com-20140222021049-g04nwe512x430tk5
Windowing system distributor `Microsoft Corp.', version 6.1.7601
Configured using:
 `configure --prefix=/c/Devel/emacs/binary --enable-checking=yes,glyphs
 'CFLAGS=-O0 -g3' LDFLAGS=-Lc:/Devel/emacs/lib
 CPPFLAGS=-Ic:/Devel/emacs/include'