Merge branch 'nd/misc-cleanups'

Merge branch 'nd/misc-cleanups'

* nd/misc-cleanups:
  unpack_object_header_buffer(): clear the size field upon error
  tree_entry_interesting: make use of local pointer "item"
  tree_entry_interesting(): give meaningful names to return values
  read_directory_recursive: reduce one indentation level
  get_tree_entry(): do not call find_tree_entry() on an empty tree
  tree-walk.c: do not leak internal structure in tree_entry_len()