submodule update: test recursive path reporting from subdirectory

This patch is just a test and fixes no bug as there is currently no bug
in the path handling of `submodule update`.

In `submodule update` we make a call to `submodule--helper list --prefix
"$wt_prefix"` which looks a bit brittle and likely to introduce a bug
for the path handling. It is not a bug as the prefix is ignored inside
the submodule helper for now. If this test breaks eventually, we want
to make sure the `wt_prefix` is passed correctly into recursive submodules.
Hint: In recursive submodules we expect `wt_prefix` to be empty.

Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: stefanbeller

t/t7406-submodule-update.sh

@@ -379,6 +379,26 @@ test_expect_success 'submodule update - command in .git/config catches failure -
 	test_cmp actual expect
 '
 
+cat << EOF >expect
+Execution of 'false $submodulesha1' failed in submodule path '../super/submodule'
+Failed to recurse into submodule path '../super'
+EOF
+
+test_expect_success 'recursive submodule update - command in .git/config catches failure -- subdirectory' '
+	(cd recursivesuper &&
+	 git submodule update --remote super &&
+	 git add super &&
+	 git commit -m "update to latest to have more than one commit in submodules"
+	) &&
+	git -C recursivesuper/super config submodule.submodule.update "!false" &&
+	git -C recursivesuper/super/submodule reset --hard $submodulesha1^ &&
+	(cd recursivesuper &&
+	 mkdir -p tmp && cd tmp &&
+	 test_must_fail git submodule update --recursive ../super 2>../../actual
+	) &&
+	test_cmp actual expect
+'
+
 test_expect_success 'submodule init does not copy command into .git/config' '
 	(cd super &&
 	 H=$(git ls-files -s submodule | cut -d" " -f2) &&