dir-spec never got updated with new Fast / Guard cutoffs
dir-spec.txt still says
"Fast" -- A router is 'Fast' if it is active, and its bandwidth is
either in the top 7/8ths for known active routers or at least some
minimum (20KB/s until 0.2.3.7-alpha, and 100KB/s after that).
and
"Guard" -- A router is a possible 'Guard' if its Weighted Fractional
Uptime is at least the median for "familiar" active routers, and if
its bandwidth is at least median or at least 250KB/s.
yet we changed these numbers in 0.2.5.6-alpha (#12690 (moved)), and actually we even changed 'median' to '3/4' for guard. We should update the dir-spec.