Merge branch 'jt/sparse-checkout-leading-dir-fix'

"git sparse-checkout init" failed to write into $GIT_DIR/info
directory when the repository was created without one, which has
been corrected to auto-create it.

* jt/sparse-checkout-leading-dir-fix:
  sparse-checkout: create leading directory

builtin/sparse-checkout.c

@@ -471,6 +471,9 @@ static int sparse_checkout_init(int argc, const char **argv)
 		FILE *fp;
 
 		/* assume we are in a fresh repo, but update the sparse-checkout file */
+		if (safe_create_leading_directories(sparse_filename))
+			die(_("unable to create leading directories of %s"),
+			    sparse_filename);
 		fp = xfopen(sparse_filename, "w");
 		if (!fp)
 			die(_("failed to open '%s'"), sparse_filename);

t/t1091-sparse-checkout-builtin.sh

@@ -79,6 +79,12 @@ test_expect_success 'git sparse-checkout init' '
 	check_files repo a
 '
 
+test_expect_success 'git sparse-checkout init in empty repo' '
+	test_when_finished rm -rf empty-repo blank-template &&
+	git init --template= empty-repo &&
+	git -C empty-repo sparse-checkout init
+'
+
 test_expect_success 'git sparse-checkout list after init' '
 	git -C repo sparse-checkout list >actual &&
 	cat >expect <<-\EOF &&