`setopt append_history` is not necessary.

Especially given the inc_append_history option, it is not necessary to
set the (default) append_history option.

lib/history.zsh

@@ -3,7 +3,6 @@ HISTFILE=$HOME/.zsh_history
 HISTSIZE=10000
 SAVEHIST=10000
 
-setopt append_history
 setopt extended_history
 setopt hist_expire_dups_first
 setopt hist_ignore_dups # ignore duplication command history list