Pluggable Transports + proxy is not working on Windows with Tor Browser

While PTs + proxy are working fine on Linux and Mac OS X they are broken on Windows:

12.06.2014 14:22:10.893 [WARN] Managed proxy failed to configure the pluggable transport's outgoing proxy. (We don't have txsocksx. Can't do proxy. Please install txsocksx.) 
12.06.2014 14:22:10.894 [WARN] Managed proxy at 'Tor\PluggableTransports\obfsproxy' failed the configuration protocol and will be destroyed.