503 when downloading via fastly

A travis job just barfed because of the following.

$ sudo snap install lxd --channel 3.0/stable
error: cannot perform the following tasks:
- Download snap "lxd" (8715) from channel "3.0/stable" (received an unexpected http response code (503) when trying to download https://fastly.cdn.snapcraft.io/download-origin/fastly/J60k4JY0HppjwOjW8dZdYc8obXKxujRu_8715.snap?token=1539050400_b8fc9cec6b6f76cb9fc3bb73d0c2a9861c98f569)

I can’t exactly retrospectively enable debug to find out what happened, and I’m somewhat loathed to enable debug on a travis job as it makes it hard to see the wood for the trees when debugging my own problems.

What do we do when the store or cache or whatever barfs like this? I can of course re-launch the job. Anything else?