We fixed bug 539 (where directories would say "503" but send data
anyway) back in 0.2.0.16-alpha/0.1.2.19. Because most directory
versions were affected, we added workaround to make sure that we
examined the contents of 503-replies to make sure there wasn't any
data for them to find. But now that such routers are nonexistent,
we can remove this code. (Even if somebody fired up an 0.1.2.19
directory cache today, it would still be fine to ignore data in its
erroneous 503 replies.)