502 Bad Gateway when updating from custom apt repo

Travis builds which had previously been working are no longer.
I am serving up custom debian packages in a repo I host. When I run apt-get update, I get a 502 Bad Gateway error on that repo. However, I changed the install script to also wget the Packages file and it has no problem. Looking at the server side of things, I don’t see apt-get even trying to contact my server, but I do see wget hitting it. Any suggestions? Here’s a sample job failure:

https://travis-ci.org/libffi/libffi/jobs/550732021

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