Regression in git master: Can't bootstrap with bridges

I was trying to track down an issue in stegotorus when I found that current Tor master has a problem bootstrapping. I'm using this configuration

bridge XX:995
bridge XX:443
Bridge XX:5251

CircuitBuildTimeout 60

UseBridges 1

(With real bridges, of course.)

After bisecting, it appears that d7089ff2 is at fault. Oops -- that's one of mine. :p

The failure mode here is that we get up to 50% bootstrapped, then:

Feb 28 16:58:46.000 [notice] Bootstrapped 20%: Asking for networkstatus consensus.
Feb 28 16:58:46.000 [notice] Bootstrapped 50%: Loading relay descriptors.
Feb 28 16:58:47.000 [notice] Learned fingerprint XXX for bridge XX:5251.
Feb 28 16:58:47.000 [notice] Learned fingerprint XXX for bridge XX:443.

and then no further.

Any insights for what I screwed up with d7089ff2 ?