In emacs 28 "when" parameter are mandatory in function define-obsolete-variable-alias

[vpxyz]

In emacs 28 (master branch), the "when" parameter are mandatory in functions make-obsolete, define-obsolete-function-alias, make-obsolete-variable and define-obsolete-variable-alias.
The issue in caused by the line 4878:
(define-obsolete-variable-alias 'projectile-mode-line-lighter 'projectile-mode-line-prefix)

Expected behavior

projectile run as usual

Actual behavior

emacs are unable to load projectile:

  #f(compiled-function (obsolete-name current-name when &optional docstring) "Make OBSOLETE-NAME a variable alias for CURRENT-NAME and mark it obsolete.....)  
(define-obsolete-variable-alias 'projectile-mode-line-lighter 'projectile-mode-line-prefix)
  eval-buffer(#<buffer  *load*-693182> nil "/home/vincenzo/.emacs.d/elpa/projectile-20210104.7..." nil t)  ; Reading at buffer position 208182

Steps to reproduce the problem

Load projectile with emacs 28 (master branch)

Environment & Version information

Projectile version information

Projectile 20210104.700

Emacs version

GNU Emacs 28.0.50 (build 31, x86_64-pc-linux-gnu, GTK+ Version 3.24.24, cairo version 1.16.0)
of 2021-01-04

Operating system

Fedora 33

[bbatsov]

Thanks for reporting this!