[docker_test.sh] Fix checkout path

docker_test.sh

@@ -59,20 +59,18 @@ read ans
 
 if [ $ans == "y" ]; then
   git pull
-  git checkout -- $1
+  if [[ ! -d "$1" ]]; then
+    echo "ERROR : directory does not exist ($1)"
+    usage
+    exit 1
+  fi
+  cd "$1"
+  git checkout -- .
 else
   echo "Aborting."
   exit 0
 fi
 
-if [[ ! -d "$1" ]]; then
-  echo "ERROR : directory does not exist ($1)"
-  usage
-  exit 1
-fi
-
-cd "$1"
-
 create_dumb_secrets
 
 echo -e "\n==== Remove and re-create named external volumes ===="