Merge pull request #750 from blueyed/history-drop-default-append-history

`setopt append_history` is not necessary.

lib/history.zsh

@@ -5,7 +5,6 @@ fi
 HISTSIZE=10000
 SAVEHIST=10000
 
-setopt append_history
 setopt extended_history
 setopt hist_expire_dups_first
 setopt hist_ignore_dups # ignore duplication command history list