Merge branch 'sj/untracked-files-in-submodule-directory-is-not-dirty'

"git diff" showed a submodule working tree with untracked cruft as
"Submodule commit <objectname>-dirty", but a natural expectation is
that the "-dirty" indicator would align with "git describe --dirty",
which does not consider having untracked files in the working tree
as source of dirtiness.  The inconsistency has been fixed.

* sj/untracked-files-in-submodule-directory-is-not-dirty:
  diff: do not show submodule with untracked files as "-dirty"

t/t3701-add-interactive.sh

@@ -849,6 +849,12 @@ test_expect_success 'setup different kinds of dirty submodules' '
 	cat >expected <<-\EOF &&
 	dirty-both-ways
 	dirty-head
+	EOF
+	test_cmp expected actual &&
+	git -C for-submodules diff-files --name-only --ignore-submodules=none >actual &&
+	cat >expected <<-\EOF &&
+	dirty-both-ways
+	dirty-head
 	dirty-otherwise
 	EOF
 	test_cmp expected actual &&