Actually stdin being inherited is a general problem

test/test-pointer.sh

@@ -95,8 +95,8 @@ begin_test "pointer --stdin without stdin"
 (
   # this test doesn't work on Windows, it just operates like 'bad pointer' case
   # stdin isn't detectable as detached, it just times out with no content
-  if [ "$IS_WINDOWS" != "0" ]; then
-    echo "Skipping pointer without stdin because Windows doesn't have detached stdin"
+  if [[ "$(is_stdin_attached)" == "0" ]]; then
+    echo "Skipping pointer without stdin because STDIN attached"
     exit 0
   fi
   output=$(echo "" | git lfs pointer --stdin 2>&1)

test/testhelpers.sh

@@ -403,3 +403,9 @@ contains_same_elements() {
 
   [ "$a" == "$b" ]
 }
+
+
+is_stdin_attached() {
+  test -t0
+  echo $?
+}