It is not you; the Linaro repository has been intermittently down since the middle of last week.
This post in a thread of mine has a possible fix: https://groups.google.com/d/msg/beagleboard/2Q3QlnQNvOQ/GvBG4LoHQXoJ
I tried this myself, but never got it to work. When I tried to build systemd-image from stock (no modifying the Linaro URL’s) yesterday (Sunday morning on the east coast of the US), it completed fine.
Dave M.