tests: worktree/bare: fix git_worktree_validate

src/worktree.c

@@ -248,7 +248,7 @@ int git_worktree_validate(const git_worktree *wt)
 		goto out;
 	}
 
-	if (!git_path_exists(wt->parent_path)) {
+	if (wt->parent_path && !git_path_exists(wt->parent_path)) {
 		giterr_set(GITERR_WORKTREE,
 			"Worktree parent directory ('%s') does not exist ",
 			wt->parent_path);

tests/worktree/bare.c

@@ -42,6 +42,8 @@ void test_worktree_bare__add(void)
 	cl_git_pass(git_worktree_list(&wts, g_repo));
 	cl_assert_equal_i(wts.count, 1);
 
+	cl_git_pass(git_worktree_validate(wt));
+
 	cl_git_pass(git_repository_open(&wtrepo, WORKTREE_REPO));
 	cl_assert_equal_i(0, git_repository_is_bare(wtrepo));
 	cl_assert_equal_i(1, git_repository_is_worktree(wtrepo));