BridgeDB will sometimes return no obfs2 or obfs3 bridges over html
I am unable to reproduce this with any regularity, but I have seen it happen twice now. Sometimes when you visit https://bridges.torproject.org/bridges you will only recieve standard bridges and no obfs2 or obfs3 bridges. This is especially problematic if you are coming from a fixed IP address (e.g. not tor) and need an obfsproxy transport, since you will then have to wait some length of time until your new request for bridges will get you a new set of bridges.