fix panic in object.Tree.FindEntry

plumbing/object/tree.go

@@ -135,7 +135,7 @@ func (t *Tree) FindEntry(path string) (*TreeEntry, error) {
 	pathCurrent := ""
 
 	// search for the longest path in the tree path cache
-	for i := len(pathParts); i > 1; i-- {
+	for i := len(pathParts) - 1; i > 1; i-- {
 		path := filepath.Join(pathParts[:i]...)
 
 		tree, ok := t.t[path]

plumbing/object/tree_test.go

@@ -125,6 +125,9 @@ func (s *TreeSuite) TestFindEntryNotFound(c *C) {
 	e, err := s.Tree.FindEntry("not-found")
 	c.Assert(e, IsNil)
 	c.Assert(err, Equals, ErrEntryNotFound)
+	e, err = s.Tree.FindEntry("not-found/not-found/not-found")
+	c.Assert(e, IsNil)
+	c.Assert(err, Equals, ErrDirectoryNotFound)
 }
 
 // Overrides returned plumbing.EncodedObject for given hash.