Do you have a webfilter appliance?
You may have to add launchpad.net to the whitelist, or the bypass list so that the traffic is not monitored?
We filter all traffic anything ssl gets decrypted and sent down to the client (basically a man in the middle) and I had to add the url to the bypass list so the traffic is not decrypted.
I could get to the website fine, but I saw issues with adding the repository. (I even added the repo to the sources.list which helped some but not completely.)