revision.c: remove implicit dependency on the_index

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/diff-files.c

@@ -25,7 +25,7 @@ int cmd_diff_files(int argc, const char **argv, const char *prefix)
 		usage(diff_files_usage);
 
 	git_config(git_diff_basic_config, NULL); /* no "diff" UI options */
-	init_revisions(&rev, prefix);
+	repo_init_revisions(the_repository, &rev, prefix);
 	rev.abbrev = 0;
 	precompose_argv(argc, argv);