update cache for conflicting submodule entries

When merging merge bases during a recursive merge we do not want to
leave any unmerged entries. Otherwise we cannot create a temporary
tree for the recursive merge to work with.

We failed to do so in case of a submodule conflict between merge
bases, causing a NULL pointer dereference in the next step of the
recursive merge.

Signed-off-by: Clemens Buchacher <drizzd@aon.at>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

merge-recursive.c

@@ -1123,10 +1123,11 @@ static int process_entry(struct merge_options *o,
 		clean_merge = mfi.clean;
 		if (mfi.clean)
 			update_file(o, 1, mfi.sha, mfi.mode, path);
-		else if (S_ISGITLINK(mfi.mode))
+		else if (S_ISGITLINK(mfi.mode)) {
 			output(o, 1, "CONFLICT (submodule): Merge conflict in %s "
 			       "- needs %s", path, sha1_to_hex(b.sha1));
-		else {
+			update_file(o, 0, mfi.sha, mfi.mode, path);
+		} else {
 			output(o, 1, "CONFLICT (%s): Merge conflict in %s",
 					reason, path);
 

t/t7405-submodule-merge.sh

@@ -63,7 +63,7 @@ test_expect_failure 'merging with modify/modify conflict' '
 
 '
 
-test_expect_failure 'merging with a modify/modify conflict between merge bases' '
+test_expect_success 'merging with a modify/modify conflict between merge bases' '
 
 	git reset --hard HEAD &&
 	git checkout -b test2 c &&