buildNodePackage: fix strippedName usage

pkgs/development/node-packages/node-env.nix

@@ -121,7 +121,7 @@ let
       if [ -f "${src}" ]
       then
           # Figure out what directory has been unpacked
-          packageDir=$(find . -type d -maxdepth 1 | tail -1)
+          packageDir="$(find . -type d -maxdepth 1 | tail -1)"
           
           # Restore write permissions to make building work
           find "$packageDir" -type d -print0 | xargs -0 chmod u+x
@@ -131,6 +131,8 @@ let
           mv "$packageDir" "$DIR/${packageName}"
       elif [ -d "${src}" ]
       then
+          strippedName="$(stripHash ${src})"
+
           # Restore write permissions to make building work
           chmod -R u+w $strippedName
           
@@ -138,9 +140,6 @@ let
           mv $strippedName "$DIR/${packageName}"
       fi
 
-      # Unset the stripped name to not confuse the next unpack step
-      unset strippedName
-      
       # Some version specifiers (latest, unstable, URLs, file paths) force NPM to make remote connections or consult paths outside the Nix store.
       # The following JavaScript replaces these by * to prevent that
       cd "$DIR/${packageName}"