fast-export: Set revs.topo_order before calling setup_revisions

setup_revisions sets a variety of flags based on the setting of other
flags, such as setting the limited flag when topo_order is set.  To avoid
circumventing any invariants created by setup_revisions, we set
revs.topo_order before calling it rather than after.

Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin-fast-export.c

@@ -514,6 +514,7 @@ int cmd_fast_export(int argc, const char **argv, const char *prefix)
 	git_config(git_default_config, NULL);
 
 	init_revisions(&revs, prefix);
+	revs.topo_order = 1;
 	argc = setup_revisions(argc, argv, &revs, NULL);
 	argc = parse_options(argc, argv, prefix, options, fast_export_usage, 0);
 	if (argc > 1)
@@ -524,7 +525,6 @@ int cmd_fast_export(int argc, const char **argv, const char *prefix)
 
 	get_tags_and_duplicates(&revs.pending, &extra_refs);
 
-	revs.topo_order = 1;
 	if (prepare_revision_walk(&revs))
 		die("revision walk setup failed");
 	revs.diffopt.format_callback = show_filemodify;