When a client has UseBridges set to 1, and it has a cached microdesc consensus in its datadir, when it starts up it loads that consensus file from disk, and calls `networkstatus_set_current_consensus()` on it. That function checks ``` if (flav != usable_consensus_flavor() && !directory_caches_dir_info(options)) { /* This consensus is totally boring to us: we won't use it, and we won't * serve it. Drop it. */ goto done; } ``` and in this case, `usable_consensus_flavor()` checks `we_use_microdescriptors_for_circuits()` which decides ``` /* If we are configured to use bridges and none of our bridges * know what a microdescriptor is, the answer is no. */ if (options->UseBridges && !any_bridge_supports_microdescriptors()) return 0; ``` That is, if you have bridges but you haven't marked any of them up yet, then you default to using the old-flavor consensus, so when you read your microdesc-consensus from disk, you quietly discard it. This bug results in bridge users always fetching a new consensus at start, even when they don't need to. (Bug reported by [a person who was helpful at first but now seems to be trying to distract me and prevent me from fixing Tor bugs].)