Currently, when we set `DirAuthorities` or `AlternateDirAuthority`, we don't add the default directory authorities. But, (as long as `FallbackDir` isn't set) we do add the default fallback directories. It doesn't make sense to me to add the default fallback directories when we have custom `DirAuthorities` or `AlternateDirAuthority`. I think we should only add the default fallback directories when other directories are also set to their defaults. However, the list of default fallback directories is currently `NULL`, so this issue currently has no effect. I also can't imagine any scenarios where it would be useful to set an `AlternateDirAuthority` or `DirAuthorities`, and still get the default `FallbackDir`. I can imagine this causing similar issues to legacy/trac#13163, where the default authorities were added to a custom set of authorities in some circumstances. I'll create a patch to fix this, but it won't actually change tor's observable behaviour until we add directories to the default fallback directory list. Bugfix on 90f6071d8dc0 in 0.2.4.7-alpha.