submodule--helper: die on config error when cloning module

When setting the 'core.worktree' option for a newly cloned
submodule we ignore the return value of `git_config_set_in_file`.
As this leaves the submodule in an inconsistent state, we instead
want to inform the user that something has gone wrong by printing
an error and aborting the program.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/submodule--helper.c

@@ -245,8 +245,8 @@ static int module_clone(int argc, const char **argv, const char *prefix)
 	p = git_pathdup_submodule(path, "config");
 	if (!p)
 		die(_("could not get submodule directory for '%s'"), path);
-	git_config_set_in_file(p, "core.worktree",
-			       relative_path(sb.buf, sm_gitdir, &rel_path));
+	git_config_set_in_file_or_die(p, "core.worktree",
+				      relative_path(sb.buf, sm_gitdir, &rel_path));
 	strbuf_release(&sb);
 	strbuf_release(&rel_path);
 	free(sm_gitdir);