NumDirectoryGuards should track NumEntryGuards
If you change NumEntryGuards to 1, your Tor will still contact 3 relays for directory information, since you didn't realize you had to set NumDirectoryGuards too. This fails the 'no surprises' principle.
At the same time, we have this check:
if (options->UseEntryGuards && ! options->NumEntryGuards) REJECT("Cannot enable UseEntryGuards with NumEntryGuards set to 0");
but no corresponding check for "UseEntryGuardsAsDirGuards 1 but NumDirectoryGuards 0".
I think the right behavior should be to treat NumDirectoryGuards 0 as "use the value from numentryguards", and change that to the default.
Bug encountered by Isis.