Merge branch 'ds/lazy-load-trees'

The code has been taught to use the duplicated information stored
in the commit-graph file to learn the tree object name for a commit
to avoid opening and parsing the commit object when it makes sense
to do so.

* ds/lazy-load-trees:
  coccinelle: avoid wrong transformation suggestions from commit.cocci
  commit-graph: lazy-load trees for commits
  treewide: replace maybe_tree with accessor methods
  commit: create get_commit_tree() method
  treewide: rename tree to maybe_tree

sha1-name.c

@@ -864,7 +864,7 @@ struct object *peel_to_type(const char *name, int namelen,
 		if (o->type == OBJ_TAG)
 			o = ((struct tag*) o)->tagged;
 		else if (o->type == OBJ_COMMIT)
-			o = &(((struct commit *) o)->tree->object);
+			o = &(get_commit_tree(((struct commit *)o))->object);
 		else {
 			if (name)
 				error("%.*s: expected %s type, but the object "