object: add repository argument to parse_object

Add a repository argument to allow the callers of parse_object
to be more specific about which repository to act on. This is a small
mechanical change; it doesn't change the implementation to handle
repositories other than the_repository yet.

As with the previous commits, use a macro to catch callers passing a
repository other than the_repository at compile time.

Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

tree.c

@@ -8,6 +8,7 @@
 #include "tag.h"
 #include "alloc.h"
 #include "tree-walk.h"
+#include "repository.h"
 
 const char *tree_type = "tree";
 
@@ -244,7 +245,7 @@ void free_tree_buffer(struct tree *tree)
 
 struct tree *parse_tree_indirect(const struct object_id *oid)
 {
-	struct object *obj = parse_object(oid);
+	struct object *obj = parse_object(the_repository, oid);
 	do {
 		if (!obj)
 			return NULL;
@@ -257,6 +258,6 @@ struct tree *parse_tree_indirect(const struct object_id *oid)
 		else
 			return NULL;
 		if (!obj->parsed)
-			parse_object(&obj->oid);
+			parse_object(the_repository, &obj->oid);
 	} while (1);
 }