It appears as if the '9.5' component apt repo metadata is not generating
properly. Although 9.5 packages are available under the 'main' component
and package metadata exists for all other version specific components (9.3,
9.4, 9.6, etc) the 9.5 component is missing package lists under all
distributions (trusty-pgdg, wheezy-pgdg, xenial-pgdg, etc) for both i386
and amd64 architectures.
You can see the Packages files are empty, for example
http://apt.postgresql.org/pub/repos/apt/dists/trusty-pgdg/9.5/binary-amd64/Packages
http://apt.postgresql.org/pub/repos/apt/dists/xenial-pgdg/9.5/binary-i386/Packages
Thanks
-Peter