obfs3 transport is broken in Tor Browser nightlies

While testing my fix for #17428 (closed) I stumbled over broken obfs3 in our nightly builds:

Jan 15 11:34:14.000 [warn] 2 connections have failed: Jan 15 11:34:14.000 [warn] 1 connections died in state handshaking (TLS) with SSL state SSLv2/v3 read server hello A in HANDSHAKE Jan 15 11:34:14.000 [warn] 1 connections died in state handshaking (proxy) with SSL state (No SSL object) Jan 15 11:34:14.000 [warn] The connection to the SOCKS5 proxy server at 127.0.0.1:45701 just failed. Make sure that the proxy server is up and running.

Nightlies can be found on https://people.torproject.org/~linus/builds/