worktree: allow manual ignore patterns when no .gitignore is available

worktree_status.go

@@ -142,12 +142,16 @@ func (w *Worktree) diffStagingWithWorktree(reverse bool) (merkletrie.Changes, er
 
 func (w *Worktree) excludeIgnoredChanges(changes merkletrie.Changes) merkletrie.Changes {
 	patterns, err := gitignore.ReadPatterns(w.Filesystem, nil)
-	if err != nil || len(patterns) == 0 {
+	if err != nil {
 		return changes
 	}
 
 	patterns = append(patterns, w.Excludes...)
 
+	if len(patterns) == 0 {
+		return changes
+	}
+
 	m := gitignore.NewMatcher(patterns)
 
 	var res merkletrie.Changes

worktree_test.go

@@ -1129,6 +1129,34 @@ func (s *WorktreeSuite) TestIgnored(c *C) {
 	c.Assert(file.Worktree, Equals, Untracked)
 }
 
+func (s *WorktreeSuite) TestExcludedNoGitignore(c *C) {
+	f := fixtures.ByTag("empty").One()
+	r := s.NewRepository(f)
+
+	fs := memfs.New()
+	w := &Worktree{
+		r:          r,
+		Filesystem: fs,
+	}
+
+	_, err := fs.Open(".gitignore")
+	c.Assert(err, Equals, os.ErrNotExist)
+
+	w.Excludes = make([]gitignore.Pattern, 0)
+	w.Excludes = append(w.Excludes, gitignore.ParsePattern("foo", nil))
+
+	err = util.WriteFile(w.Filesystem, "foo", []byte("FOO"), 0755)
+	c.Assert(err, IsNil)
+
+	status, err := w.Status()
+	c.Assert(err, IsNil)
+	c.Assert(status, HasLen, 0)
+
+	file := status.File("foo")
+	c.Assert(file.Staging, Equals, Untracked)
+	c.Assert(file.Worktree, Equals, Untracked)
+}
+
 func (s *WorktreeSuite) TestAddModified(c *C) {
 	fs := memfs.New()
 	w := &Worktree{