POST hook doesn't seem to work if the url contains auth data

I am trying to integrate bitbucket with our private CI system (buildbot), and bitbucket doesn't seem to run the hook (or it crashes somehow)

the POST url is something along the lines of
http://user:password@buildbot.domain.com/change_hook/bitbucket

another instance where I don't use authentication works fine, so I guess it doesn't like the user:password part?