sh.zio.update-rootfs: fix incorrect git logic

usr/local/bin/sh.zio.update-rootfs

@@ -9,11 +9,12 @@ fi
 # TODO: Check if we're actually using the rootfs git
 
 test_root
+test_prog "git"
 
 orig_dir="$(pwd)"
 cd /
 
+git fetch --all
 git reset --hard origin main
-git pull
 
 cd $orig_dir