BridgeDB hidden service doesn't show captcha images.
BridgeDB hidden service doesn't show images when asked to type captcha: http://z5tfsnikzulwicxs.onion/bridges?transport=obfs4
(for verification purpose you can use https://onion.torproject.org/ instead of above URL to find hidden service for bridges.torproject.org)
Trac:
Username: righnaw