Trying to switch from a direct connection to using a bridge is not working anymore with tor on `master` (found while using commit f2f1cab2b3c6a56f93862c424663f083b79c7bc3) on my Linux box. Steps to reproduce: 1) Take a recent Tor Browser (e.g. an alpha version) 2) Make sure you replace `tor` shipped in your Tor Browser instance with one compiled from a recent master commit 3) Start Tor Browser and choose direct connection 4) Shut Tor Browser down after you got greeted with the `about:tor` page 5) Restart Tor Browser and press the "Open Settings" button before the bootstrapping is finished 6) Select e.g. the recommended `obfs4` default bridge option 7) The start-up stalls (I quit Tor Browser after 5 minutes waiting) The first bad commit is c21cfd28f43a969229ede02e20c6b554c1b88aae which fixed legacy/trac#17750. Without that one Tor Browser resumes bootstrapping after a couple of seconds and is using an `obfs4` bridge.