[readme] optimize calling of nvm version in zsh

Author: robertshuford

README.md

@@ -613,18 +613,17 @@ Put this into your `$HOME/.zshrc` to call `nvm use` automatically whenever you e
 # place this after nvm initialization!
 autoload -U add-zsh-hook
 load-nvmrc() {
-  local node_version="$(nvm version)"
   local nvmrc_path="$(nvm_find_nvmrc)"
 
   if [ -n "$nvmrc_path" ]; then
     local nvmrc_node_version=$(nvm version "$(cat "${nvmrc_path}")")
 
     if [ "$nvmrc_node_version" = "N/A" ]; then
       nvm install
-    elif [ "$nvmrc_node_version" != "$node_version" ]; then
+    elif [ "$nvmrc_node_version" != "$(nvm version)" ]; then
       nvm use
     fi
-  elif [ "$node_version" != "$(nvm version default)" ]; then
+  elif [ -n "$(PWD=$OLDPWD nvm_find_nvmrc)" ] && [ "$(nvm version)" != "$(nvm version default)" ]; then
     echo "Reverting to nvm default version"
     nvm use default
   fi