Merge branch 'jc/index-output'

* jc/index-output:
  git-read-tree --index-output=<file>
  _GIT_INDEX_OUTPUT: allow plumbing to output to an alternative index file.

Conflicts:

	builtin-apply.c

builtin-update-index.c

@@ -495,7 +495,7 @@ int cmd_update_index(int argc, const char **argv, const char *prefix)
 	/* We can't free this memory, it becomes part of a linked list parsed atexit() */
 	lock_file = xcalloc(1, sizeof(struct lock_file));
 
-	newfd = hold_lock_file_for_update(lock_file, get_index_file(), 0);
+	newfd = hold_locked_index(lock_file, 0);
 	if (newfd < 0)
 		lock_error = errno;
 
@@ -661,7 +661,7 @@ int cmd_update_index(int argc, const char **argv, const char *prefix)
 			    get_index_file(), strerror(lock_error));
 		}
 		if (write_cache(newfd, active_cache, active_nr) ||
-		    close(newfd) || commit_lock_file(lock_file))
+		    close(newfd) || commit_locked_index(lock_file))
 			die("Unable to write new index file");
 	}