scripts/cd in rvm-1.0.2 vs scripts/cd in rvm-1.0.3

@@ -1,10 +1,11 @@
 #!/usr/bin/env bash
 
 # Source a .rvmrc file in a directory after changing to it, if it exists.
 # To disable this fature, set rvm_project_rvmrc=0 in $HOME/.rvmrc
-if [[ "$rvm_project_rvmrc" -ne 0 ]] ; then
-  if [[ -n "$ZSH_VERSION" ]]; then
+rvm_project_rvmrc=${rvm_project_rvmrc:-1}
+if [[ $rvm_project_rvmrc -ne 0 ]] ; then
+  if [[ -n "${ZSH_VERSION:-""}" ]] ; then
     autoload is-at-least
     if is-at-least 4.3.4 >/dev/null 2>&1; then
       # On zsh, use chpwd_functions
       chpwd_functions=( "${chpwd_functions[@]}" __rvm_project_rvmrc )
     else