bug#51029: 28.0.60; ibuffer-shrink-to-fit: Symbol’s value as variable is void: ibuffer-auto-mode

[Y . E .]

*** Steps to reproduce:

1. emacs -Q
2. Optionally: (require 'ibuffer)
3. (setq ibuffer-default-shrink-to-minimum-size t)
4. M-x ibuffer


*** Result:

*Messages*

Updating buffer list...
Formats have changed, recompiling...done
Updating buffer list...done
ibuffer-shrink-to-fit: Symbol’s value as variable is void: ibuffer-auto-mode


*Backtrace*

Debugger entered--Lisp error: (void-variable ibuffer-auto-mode)
  buffer-local-value(ibuffer-auto-mode #<buffer *Ibuffer*>)
  ibuffer-shrink-to-fit()
  ibuffer-update(nil)
  ibuffer(nil)
  funcall-interactively(ibuffer nil)
  call-interactively(ibuffer record nil)
  command-execute(ibuffer record)
  execute-extended-command(nil "ibuffer" #("ibu" 0 2 (fontified t) 2 3 
(fontified nil)))
  funcall-interactively(execute-extended-command nil "ibuffer" #("ibu" 0 2 
(fontified t) 2 3 (fontified nil)))
  call-interactively(execute-extended-command nil nil)
  command-execute(execute-extended-command)


In GNU Emacs 28.0.60 (build 1, x86_64-apple-darwin18.7.0, NS appkit-1671.60 
Version 10.14.6 (Build 18G9216))
 of 2021-10-01
Repository revision: 5ee5a90213f6a6cac31fc849af6bf152756292e3
Repository branch: emacs-28
Windowing system distributor 'Apple', version 10.3.1671
System Description:  Mac OS X 10.14.6