[PATCH 2/2] submodule.c: warn about missing submodule git directories

[Stefan Beller <sbeller@google.com>]

This is the continuation of f2d48994dc1 (submodule.c: submodule_move_head
works with broken submodules, 2017-04-18), which tones down the case of
"broken submodule" in case of a missing git directory of the submodule to
be only a warning.

Signed-off-by: Stefan Beller <sbeller@google.com>
---
 submodule.c                   | 16 ++++++++++++++++
 t/t2013-checkout-submodule.sh |  2 +-
 2 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/submodule.c b/submodule.c
index 50cbf5f13ed..689439a3d0c 100644
--- a/submodule.c
+++ b/submodule.c
@@ -1641,6 +1641,22 @@ int submodule_move_head(const char *path,
 		} else {
 			char *gitdir = xstrfmt("%s/modules/%s",
 				    get_git_common_dir(), sub->name);
+
+			if (!is_git_directory(gitdir)) {
+				/*
+				 * It is safe to assume we could just clone
+				 * the submodule here, as we passed the
+				 * is_submodule_active test above (i.e. the
+				 * user is interested in this submodule.
+				 *
+				 * However as this code path is exercised
+				 * for operations that typically do not involve
+				 * network operations, let's not do that for now.
+				 */
+				warning(_("Submodule '%s' missing"), path);
+				free(gitdir);
+				return 0;
+			}
 			connect_work_tree_and_git_dir(path, gitdir, 0);
 			free(gitdir);
 
diff --git a/t/t2013-checkout-submodule.sh b/t/t2013-checkout-submodule.sh
index c69640fc341..82ef4576b91 100755
--- a/t/t2013-checkout-submodule.sh
+++ b/t/t2013-checkout-submodule.sh
@@ -81,7 +81,7 @@ test_expect_success 'setup superproject with historic submodule' '
 	test_must_be_empty super1/.gitmodules
 '
 
-test_expect_failure 'checkout old state with deleted submodule' '
+test_expect_success 'checkout old state with deleted submodule' '
 	test_when_finished "rm -rf super1 sub1 super1_clone" &&
 	git clone --recurse-submodules super1 super1_clone &&
 	git -C super1_clone checkout --recurse-submodules historic_state
-- 
2.18.0