[test] avoid leaking temp variable

This is to inherit $NVM_MIN from env when defined, meanwhile avoiding
inline local variable initialization for ksh compatibility.

Co-authored-by: Jordan Harband <ljharb@gmail.com>

nvm.sh

@@ -4013,9 +4013,12 @@ nvm() {
     ;;
     "ls-remote" | "list-remote")
       local NVM_LTS
-      local NVM_MIN="${NVM_MIN-}"
       local PATTERN
       local NVM_NO_COLORS
+      local NVM_MIN_ENV
+      NVM_MIN_ENV="${NVM_MIN-}"
+      local NVM_MIN
+      NVM_MIN="${NVM_MIN_ENV-}"
 
       while [ $# -gt 0 ]; do
         case "${1-}" in

test/fast/Unit tests/nvm_print_versions

@@ -8,6 +8,7 @@ cleanup() {
   unset -f nvm_remote_versions nvm_ls nvm_ls_current
   if [ -n "$TEMP_NVM_MIN" ]; then
     export NVM_MIN="$TEMP_NVM_MIN"
+    unset TEMP_NVM_MIN
   fi
 }