bug#47199: recent emacs can't do powerline anymore

[markusffm]

                      there appears only a blank mode-line, whereas in message 
buffer we read:

Error during redisplay: (eval (let* ((active (powerline-selected-window-active)) (mode-line-buffer-id (if active 'mode-line-buffer-id 
'mode-line-buffer-id-inactive)) (mode-line (if active 'mode-line 'mode-line-inactive)) (face0 (if active 'powerline-active0 'powerline-inactive0)) (face1 
(if active 'powerline-active1 'powerline-inactive1)) (face2 (if active 'powerline-active2 'powerline-inactive2)) (separator-left (intern (format 
"powerline-%s-%s" (powerline-current-separator) (car powerline-default-separator-dir)))) (separator-right (intern (format 
"powerline-%s-%s" (powerline-current-separator) (cdr powerline-default-separator-dir)))) (lhs (list (powerline-raw "%*" face0 'l) 
(when powerline-display-buffer-size (powerline-buffer-size face0 'l)) (when powerline-display-mule-info (powerline-raw mode-line-mule-info face0 'l)) 
(powerline-buffer-id `(mode-line-buffer-id ,face0) 'l) (when (and (boundp 'which-func-mode) which-func-mode) (powerline-raw which-func-format face0 'l)) 
(powerline-raw " " face0) (funcall separator-left face0 face1) (when (and (boundp 'erc-track-minor-mode) erc-track-minor-mode) (powerline-raw 
erc-modified-channels-object face1 'l)) (powerline-major-mode face1 'l) (powerline-process face1) (powerline-minor-modes face1 'l) (powerline-narrow face1 
'l) (powerline-raw " " face1) (funcall separator-left face1 face2) (powerline-vc face2 'r) (when (bound-and-true-p nyan-mode) (powerline-raw 
(list (nyan-create)) face2 'l)))) (rhs (list (powerline-raw global-mode-string face2 'r) (funcall separator-right face2 face1) (unless window-system 
(powerline-raw (char-to-string 57505) face1 'l)) (powerline-raw "%4l" face1 'l) (powerline-raw ":" face1 'l) (powerline-raw "