Fix for $path used by zsh

"The lower-case version of PATH is an array parameter
bound to the scalar upper-case parameter."
-- http://www.zsh.org/mla/users/2015/msg00178.html

nvm.sh

@@ -273,12 +273,12 @@ nvm_tree_contains_path() {
 
 # Traverse up in directory tree to find containing folder
 nvm_find_up() {
-  local path
-  path="${PWD}"
-  while [ "${path}" != "" ] && [ ! -f "${path}/${1-}" ]; do
-    path=${path%/*}
+  local path_
+  path_="${PWD}"
+  while [ "${path_}" != "" ] && [ ! -f "${path_}/${1-}" ]; do
+    path_=${path_%/*}
   done
-  nvm_echo "${path}"
+  nvm_echo "${path_}"
 }