Merge branch 'maint'

* maint:
  unpack_trees(): protect the handcrafted in-core index from read_cache()
  git-p4: Fix one-liner in p4_write_pipe function.
  Completion: add missing '=' for 'diff --diff-filter'
  Fix 'git help help'

cache.h

@@ -223,7 +223,8 @@ struct index_state {
 	struct cache_tree *cache_tree;
 	time_t timestamp;
 	void *alloc;
-	unsigned name_hash_initialized : 1;
+	unsigned name_hash_initialized : 1,
+		 initialized : 1;
 	struct hash_table name_hash;
 };