Since the 'log --graph' is slow in the repo with long history, I wanna add '--since' option for it. I tried to add the following lines in my '.spacemacs' file.
(magit-define-popup-option 'magit-log-popup ?x "Since date" "--since=" nil (org-read-date nil nil "-1y") )
but it doesn't work. so I wonder how to make it.