worktree: a worktree can be made from a bare repository

src/worktree.c

@@ -139,7 +139,7 @@ static int open_worktree_dir(git_worktree **out, const char *parent, const char
 	if ((wt->name = git__strdup(name)) == NULL
 	    || (wt->commondir_path = git_worktree__read_link(dir, "commondir")) == NULL
 	    || (wt->gitlink_path = git_worktree__read_link(dir, "gitdir")) == NULL
-	    || (wt->parent_path = git__strdup(parent)) == NULL) {
+	    || (parent && (wt->parent_path = git__strdup(parent)) == NULL)) {
 		error = -1;
 		goto out;
 	}

tests/worktree/worktree.c

@@ -228,6 +228,26 @@ void test_worktree_worktree__init(void)
 	git_repository_free(repo);
 }
 
+void test_worktree_worktree__add_from_bare(void)
+{
+	git_worktree *wt;
+	git_repository *repo, *wtrepo;
+
+	repo = cl_git_sandbox_init("short_tag.git");
+
+	cl_assert_equal_i(1, git_repository_is_bare(repo));
+	cl_assert_equal_i(0, git_repository_is_worktree(repo));
+
+	cl_git_pass(git_worktree_add(&wt, repo, "worktree-frombare", "worktree-frombare", NULL));
+	cl_git_pass(git_repository_open(&wtrepo, "worktree-frombare"));
+	cl_assert_equal_i(0, git_repository_is_bare(wtrepo));
+	cl_assert_equal_i(1, git_repository_is_worktree(wtrepo));
+
+	git_worktree_free(wt);
+	git_repository_free(repo);
+	git_repository_free(wtrepo);
+}
+
 void test_worktree_worktree__add_locked(void)
 {
 	git_worktree *wt;