Merge branch 'jk/get-oid-indexed-object-name'

The codepath to parse :<path> that obtains the object name for an
indexed object has been made more robust.

* jk/get-oid-indexed-object-name:
  get_oid: handle NULL repo->index
diff --git a/sha1-name.c b/sha1-name.c
index b4f5cad..728e6f1 100644
--- a/sha1-name.c
+++ b/sha1-name.c
@@ -1843,7 +1843,7 @@
 		if (flags & GET_OID_RECORD_PATH)
 			oc->path = xstrdup(cp);
 
-		if (!repo->index->cache)
+		if (!repo->index || !repo->index->cache)
 			repo_read_index(repo);
 		pos = index_name_pos(repo->index, cp, namelen);
 		if (pos < 0)
diff --git a/t/t7411-submodule-config.sh b/t/t7411-submodule-config.sh
index fcc0fb8..ad28e93 100755
--- a/t/t7411-submodule-config.sh
+++ b/t/t7411-submodule-config.sh
@@ -243,18 +243,14 @@
 	)
 '
 
-# When this test eventually passes, before turning it into
-# test_expect_success, remember to replace the test_i18ngrep below with
-# a "test_must_be_empty warning" to be sure that the warning is actually
-# removed from the code.
-test_expect_failure 'reading nested submodules config when .gitmodules is not in the working tree' '
+test_expect_success 'reading nested submodules config when .gitmodules is not in the working tree' '
 	test_when_finished "git -C super/submodule checkout .gitmodules" &&
 	(cd super &&
 		echo "./nested_submodule" >expect &&
 		rm submodule/.gitmodules &&
 		test-tool submodule-nested-repo-config \
 			submodule submodule.nested_submodule.url >actual 2>warning &&
-		test_i18ngrep "nested submodules without %s in the working tree are not supported yet" warning &&
+		test_must_be_empty warning &&
 		test_cmp expect actual
 	)
 '