This has been fixed since Ubuntu 16.10.
update-manager (1:16.10.3) yakkety; urgency=medium
[Nicolas Delvaux] * Attempt to retrieve Changelogs from PPA sources (LP: #253119) * Correctly detect the usage of a username in changelog URIs
-- Brian Murray <email address hidden> Wed, 27 Jul 2016 11:14:53 -0700
This has been fixed since Ubuntu 16.10.
update-manager (1:16.10.3) yakkety; urgency=medium
[Nicolas Delvaux]
* Attempt to retrieve Changelogs from PPA sources (LP: #253119)
* Correctly detect the usage of a username in changelog URIs
-- Brian Murray <email address hidden> Wed, 27 Jul 2016 11:14:53 -0700