Clients that use bridges were ignoring their cached microdesc-flavor
consensus files, because they only thought they should use the microdesc
flavor once they had a known-working bridge that could offer microdescs,
and at first boot no bridges are known-working.
This bug caused bridge-using clients to download a new microdesc consensus
on each startup.
Fixes bug 20269; bugfix on 0.2.3.12-alpha.
