[zsh] skip plugin loading in upgrade.sh

upgrade.zsh

@@ -7,5 +7,6 @@ ZSH_DOTFILES="$DOTFILES_PATH/zsh"
 git pull --rebase --stat origin master
 git submodule update --init --recursive --remote --progress
 
+ZPLG_SKIP_LOADING=1
 source "$ZSH_DOTFILES/plugins.zsh"
 zplg-upgrade

zsh/zplg.zsh

@@ -322,7 +322,9 @@ plugin() {
           fi
         done
         _zplg_debug "sourcing $script_path"
-        _zplg_load "$script_path" || return "$?"
+        if [[ -z "$ZPLG_SKIP_LOADING" ]]; then
+          _zplg_load "$script_path" || return "$?"
+        fi
       done
     done; unset load_pattern ignore_pattern script_path