Fix git rev-parse

Author: mheguy

git_update_scripts/generic-updater.sh

@@ -20,7 +20,7 @@ fi
 
 git --git-dir=/factorio/scenarios/"$folder"/.git/ --work-tree=/factorio/scenarios/"$folder"/ fetch "$repository" >/dev/null
 git --git-dir=/factorio/scenarios/"$folder"/.git/ --work-tree=/factorio/scenarios/"$folder"/ reset --hard "$repository/$branch" >/dev/null
-git rev-parse --short HEAD
+git --git-dir=/factorio/scenarios/"$folder"/.git/ --work-tree=/factorio/scenarios/"$folder"/ rev-parse --short HEAD
 
 if [ "$cleanup" = true ]; then
     echo "Deleting all map data."